What's the value of rebounding rate? (tsherkin, 2006)
Posted: Fri Apr 15, 2011 4:01 am
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tsherkin
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PostPosted: Wed Aug 09, 2006 2:15 pm Post subject: What's the value of Rebounding Rate? Reply with quote
What does it tell you?
I mean, obviously it gives you the percentage of available rebounds that a player pulled down but does it account for the quality of rebounders on your team?
I'm having a discussion with someone about Drexler versus T-Mac as a rebounder. Both of them have good peak RbR seasons but McGrady's actually had a couple of much higher RbR seasons. Does this reflect the abject lack of rebounders he usually experiences or is he just that much better a rebounder than Drexler?
Thanks!
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Chronz1
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PostPosted: Thu Aug 10, 2006 12:26 am Post subject: Reply with quote
Having a high rebound rate on a great rebounding team is more impressive than a slightly higher rating on horrible rebounding team.
Clydes rebound rate was consistantly around 9-10, even in his final days as a player with rebounding machines like Barkely and Hakeem around he was able to crash the boards at an effective rate.
Tmac has had some higher rebounding seasons but they were on squads where he was at times the best rebounder on the floor. But Id say they were close equals and you wouldnt gain much of an age by choosing either one of them. McGrady was the better defensive rebounder, but when Clyde wasnt shooting the ball he was hitting the glass alot more than Tmac does.
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deepak
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PostPosted: Thu Aug 10, 2006 12:31 am Post subject: Re: What's the value of Rebounding Rate? Reply with quote
tsherkin wrote:
What does it tell you?
I mean, obviously it gives you the percentage of available rebounds that a player pulled down but does it account for the quality of rebounders on your team?
As you say, it estimates the percentage of available rebounds a player pulls down. So, it doesn't take into account what the other teammates are doing on the boards.
Quote:
I'm having a discussion with someone about Drexler versus T-Mac as a rebounder. Both of them have good peak RbR seasons but McGrady's actually had a couple of much higher RbR seasons. Does this reflect the abject lack of rebounders he usually experiences or is he just that much better a rebounder than Drexler?
This is more a reflection of difference in position/role McGrady played, compared to Drexler. During McGrady's years in Toronto, I believe he was more a SF/PF then a SG/SF. He also averaged 2.1, 2.4, and 2.5 blocks per 40 minutes his first 3 seasons as well.
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tsherkin
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PostPosted: Thu Aug 10, 2006 12:33 am Post subject: Re: What's the value of Rebounding Rate? Reply with quote
Well, that's helpful, thanks for the answers, folks.
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gabefarkas
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PostPosted: Thu Aug 10, 2006 12:49 pm Post subject: Reply with quote
Maybe we need to come up with a RbR that compares a player's rebounds to just his teammates. Something similar to the established RbR, but only comparing to the total rebounds for a player's team, not all rebounds while he was on the floor.
That way, you could see if a guy is on a poor rebounding team and got 50% of his team's rebounds, vs if he was on a very good rebounding team and only got like 10% of his team's rebounds.
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tsherkin
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PostPosted: Thu Aug 10, 2006 1:53 pm Post subject: Reply with quote
gabefarkas wrote:
Maybe we need to come up with a RbR that compares a player's rebounds to just his teammates. Something similar to the established RbR, but only comparing to the total rebounds for a player's team, not all rebounds while he was on the floor.
That way, you could see if a guy is on a poor rebounding team and got 50% of his team's rebounds, vs if he was on a very good rebounding team and only got like 10% of his team's rebounds.
That'd be nice, some way of measuring/simulating a player's rebounding prowess on a good rebounding team. It'd be ideal for the comparison I was working with. But how would you do that?
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gabefarkas
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PostPosted: Thu Aug 10, 2006 3:41 pm Post subject: Reply with quote
tsherkin wrote:
That'd be nice, some way of measuring/simulating a player's rebounding prowess on a good rebounding team. It'd be ideal for the comparison I was working with. But how would you do that?
Well, if you have all the data to calculate RbR, I would think that the data needed to calculate what I suggested would be a subset of the RbR data, no?
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Eli W
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PostPosted: Thu Aug 10, 2006 4:22 pm Post subject: Reply with quote
You guys might be interested in Mike G and tomverve's take on a similar (though in some ways opposite) topic in this thread:
http://sonicscentral.com/apbrmetrics/vi ... .php?t=540
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tsherkin
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PostPosted: Thu Aug 10, 2006 9:30 pm Post subject: Reply with quote
gabefarkas wrote:
Well, if you have all the data to calculate RbR, I would think that the data needed to calculate what I suggested would be a subset of the RbR data, no?
So you're saying eliminate opponents rebounds from the equation?
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deepak
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PostPosted: Thu Aug 10, 2006 10:46 pm Post subject: Reply with quote
tsherkin wrote:
gabefarkas wrote:
Well, if you have all the data to calculate RbR, I would think that the data needed to calculate what I suggested would be a subset of the RbR data, no?
So you're saying eliminate opponents rebounds from the equation?
This is what I get, when I change (TmReb + OppReb) to just (TmReb) in the RebR equation. I'll call RebR the original formula, and RebR2 the newly proposed metric:
Code:
Tm Name RebR Tm Name RebR2
1 SEA/DEN Reggie Evans 21.46 1 SEA/DEN Reggie Evans 43.32
2 DEN Marcus Camby 21.05 2 DEN Marcus Camby 42.38
3 IND Jeff Foster 20.92 3 IND Jeff Foster 41.39
4 ORL Dwight Howard 20.85 4 ORL Dwight Howard 40.78
5 DAL Erick Dampier 19.96 5 MIN Kevin Garnett 40.08
6 HOU Chuck Hayes 19.65 6 HOU Chuck Hayes 38.94
7 MIN Kevin Garnett 19.58 7 CHI Tyson Chandler 38.22
8 CHI Tyson Chandler 19.35 8 DET Ben Wallace 38.18
9 DET Ben Wallace 19.01 9 DAL Erick Dampier 38.09
10 HOU Dikembe Mutombo 18.76 10 HOU Dikembe Mutombo 37.18
11 MIL Jamaal Magloire 18.74 11 PHI Samuel Dalembert 37.13
12 SAS Tim Duncan 18.68 12 MIL Jamaal Magloire 37.08
13 BOS Kendrick Perkins 18.44 13 BOS Kendrick Perkins 37.08
14 CLE Anderson Varejao 18.24 14 SAS Tim Duncan 36.84
15 CLE Drew Gooden 18.10 15 CHA Emeka Okafor 36.43
16 PHI Samuel Dalembert 17.99 16 POR Joel Przybilla 35.80
17 SAS Nazr Mohammed 17.77 17 MEM Jake Tsakalidis 35.70
18 MIA Shaquille O'Neal 17.63 18 CLE Anderson Varejao 35.20
19 MEM Jake Tsakalidis 17.53 19 MIN Eddie Griffin 35.13
20 HOU Yao Ming 17.50 20 SAS Nazr Mohammed 35.04
21 CHA Emeka Okafor 17.29 21 CLE Drew Gooden 34.93
22 MIN Eddie Griffin 17.16 22 HOU Yao Ming 34.68
23 BOS Al Jefferson 17.16 23 BOS Al Jefferson 34.50
24 LAC Chris Kaman 17.00 24 PHO Kurt Thomas 34.24
25 UTA Greg Ostertag 16.88 25 PHO Shawn Marion 34.16
26 POR Joel Przybilla 16.85 26 GSW Troy Murphy 33.79
27 UTA Carlos Boozer 16.82 27 MIA Shaquille O'Neal 33.52
28 NOH Chris Andersen 16.56 28 LAC Chris Kaman 32.8
Left columns is top 28 (minimum 500 MP), by RebR. Right column is top 28, by RebR2. As you can see, it's almost identical.
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Mike G
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PostPosted: Fri Aug 11, 2006 7:22 am Post subject: Reply with quote
In the above table, RebR2 only tells us what % of your team's rebounds you are getting. So getting 30% of the rebounds of the best-rebounding team doesn't rank you any higher than getting 30% of the worst-rebounding team's.
Going in the opposite direction -- measuring as a % of opponent rebounds -- gauges you against the rest of the league as a whole. This, to me, is the measure of how well you rebound. Otherwise, just list your team's Reb/40 or whatever.
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gabefarkas
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PostPosted: Fri Aug 11, 2006 8:49 am Post subject: Reply with quote
The biggest difference to me looks like Joel Pryzbilla. He's much higher on the RbR2 list. Could we then infer that his rebound numbers are inflated by being in a weak-rebounding team?
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gabefarkas
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PostPosted: Fri Aug 11, 2006 9:08 am Post subject: Reply with quote
So I'm trying to reconcile the two lists by doing this:
Combo = (RbR2 / 2) - (RbR)
I divide RbR2 by 2 with the assumption that if a team evenly rebounded its opponents, then Combo=0. This way, we can see guys who were genuinely good rebounders, versus guys who benefitted from being on poor rebounding teams.
There were 25 guys who were on both lists. If someone wants to provide the numbers for the missing guys, I can add them to the list.
Code:
Name RebR RebR2 Combo
Erick Dampier 19.96 38.09 -0.915
Shaquille O'Neal 17.63 33.52 -0.87
Anderson Varejao 18.24 35.2 -0.64
Drew Gooden 18.1 34.93 -0.635
Chris Kaman 17 32.8 -0.6
Dwight Howard 20.85 40.78 -0.46
Tim Duncan 18.68 36.84 -0.26
Nazr Mohammed 17.77 35.04 -0.25
Tyson Chandler 19.35 38.22 -0.24
Jeff Foster 20.92 41.39 -0.225
Jamaal Magloire 18.74 37.08 -0.2
Chuck Hayes 19.65 38.94 -0.18
Dikembe Mutombo 18.76 37.18 -0.17
Yao Ming 17.5 34.68 -0.16
Ben Wallace 19.01 38.18 0.08
Al Jefferson 17.16 34.5 0.09
Kendrick Perkins 18.44 37.08 0.1
Marcus Camby 21.05 42.38 0.14
Reggie Evans 21.46 43.32 0.2
Jake Tsakalidis 17.53 35.7 0.32
Eddie Griffin 17.16 35.13 0.405
Kevin Garnett 19.58 40.08 0.46
Samuel Dalembert 17.99 37.13 0.575
Emeka Okafor 17.29 36.43 0.925
Joel Przybilla 16.85 35.8 1.05
The way I interpret it is like this: Joel Pryzbilla benefitted from being on a weak rebounding team, thus grabbing more rebounds than his teammates otherwise might have. On the other hand, Erick Dampier was on a strong rebounding team, so his personal rebounding numbers are inflated.
Maybe I have that backwards?
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HoopStudies
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PostPosted: Fri Aug 11, 2006 9:40 am Post subject: Reply with quote
gabefarkas wrote:
The way I interpret it is like this: Joel Pryzbilla benefitted from being on a weak rebounding team, thus grabbing more rebounds than his teammates otherwise might have. On the other hand, Erick Dampier was on a strong rebounding team, so his personal rebounding numbers are inflated.
Maybe I have that backwards?
That's the thing -- we don't know. A player getting a lot of rebounds on a bad rebounding team isn't necessarily better than a player getting the same amount on a good rebounding team. Because what is "better"? The whole reason this came up is because someone subjectively believed that Drexler was a better rebounder than McGrady. But why would anyone believe this up front? Just because Drexler was one of the top 50 of all time? "Better" is completely relative to some objective. Define your objective. Define "better".
Right now, we have overall rebound rate and rebound rate relative to the team. Does either reflect a "better" rebounder?
Note that we have this same problem with the passing rating of some other thread. We don't know what "better" is, so it's hard to evaluate such a thing. Or if we wanted a "better" shooter, what is that? These reflect measures we HAVE stats for. It's a matter of defining what makes "better", doing the analysis relative to some objective. This is as opposed to defense, where the stats are so limited that defining what makes "better" is harder.
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Kevin Pelton
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PostPosted: Fri Aug 11, 2006 10:00 am Post subject: Reply with quote
I dunno, Dean, that seems way too theoretical to me.
From a practical perspective, we accept that rebounding is not linear, correct?
By that I mean that if we know the rebound rates (I don't like that term, because scoring rate means per-40 minutes generally) of the five players on the floor, simply adding them together isn't totally sufficient to find the rebound rate of that unit.
In most cases, you can safely add them up, but when you have an extremely poor rebounder or an extremely good rebounder, that player is going to have less impact on his team than it appears from his rebound rate because he's not giving/taking away all of those rebounds from the other team; some are just a redistribution of rebounds his team would get already.
Do we accept that?
Now, that being said, just looking at a team's opponents' rebounds seems to be a crude and subjective adjustment given we haven't really studied this issue in much detail and I don't think it matters much except at the extremes.
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tsherkin
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PostPosted: Fri Aug 11, 2006 10:05 am Post subject: Reply with quote
As far as "better" meant in my original question, someone was wondering if McGrady's rebounding numbers were merely because Orlando sucked and how important it was that Drexler played on good rebounding teams (in a faster-paced era).
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deepak
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PostPosted: Fri Aug 11, 2006 10:30 am Post subject: Reply with quote
The following table shows top 30, by rebound rate, as well as a few other metrics that might be of interest in this discussion.
Reb-R2: % of team's rebounds player got
R2-diff : Reb-R2/2 - Reb-R
Reb-R3: % of opponent's rebounds player got (as per Mike's suggestion)
R3-diff: Reb-R3/2 - Reb-R
R23-diff: Reb-R2 - Reb-R3
Code:
Tm Name Reb-R | Reb-R2 R2-diff | Reb-R3 R3-diff | R23-diff
----------------------------------------------------------------------------------------------
1 SEA/DEN Reggie Evans 21.79 | 44.06 0.24 | 43.09 -0.24 | 0.97
2 DEN Marcus Camby 21.05 | 42.38 0.14 | 41.82 -0.14 | 0.56
3 IND Jeff Foster 20.92 | 41.39 -0.22 | 42.28 0.23 | -0.89
4 ORL Dwight Howard 20.85 | 40.78 -0.46 | 42.64 0.48 | -1.86
5 DAL Erick Dampier 19.96 | 38.09 -0.91 | 41.94 1.01 | -3.84
6 HOU Chuck Hayes 19.65 | 38.94 -0.18 | 39.67 0.18 | -0.73
7 MIN Kevin Garnett 19.58 | 40.08 0.46 | 38.28 -0.44 | 1.80
8 CHI Tyson Chandler 19.35 | 38.22 -0.24 | 39.18 0.24 | -0.96
9 DET Ben Wallace 19.01 | 38.18 0.08 | 37.86 -0.08 | 0.32
10 HOU Dikembe Mutombo 18.76 | 37.18 -0.17 | 37.88 0.18 | -0.70
11 MIL Jamaal Magloire 18.74 | 37.08 -0.19 | 37.87 0.20 | -0.78
12 SAS Tim Duncan 18.68 | 36.84 -0.26 | 37.91 0.27 | -1.07
13 BOS Kendrick Perkins 18.44 | 37.08 0.10 | 36.69 -0.10 | 0.38
14 CLE Anderson Varejao 18.24 | 35.20 -0.64 | 37.84 0.68 | -2.64
15 CLE Drew Gooden 18.10 | 34.93 -0.63 | 37.55 0.68 | -2.62
16 PHI Samuel Dalembert 17.99 | 37.13 0.57 | 34.91 -0.54 | 2.21
17 SAS Nazr Mohammed 17.77 | 35.04 -0.25 | 36.06 0.26 | -1.02
18 MIA Shaquille O'Neal 17.63 | 33.52 -0.87 | 37.18 0.96 | -3.66
19 MEM Jake Tsakalidis 17.53 | 35.70 0.32 | 34.44 -0.31 | 1.26
20 HOU Yao Ming 17.50 | 34.68 -0.16 | 35.34 0.16 | -0.65
21 CHA Emeka Okafor 17.29 | 36.43 0.92 | 32.92 -0.83 | 3.50
22 MIN Eddie Griffin 17.16 | 35.13 0.40 | 33.55 -0.39 | 1.58
23 BOS Al Jefferson 17.16 | 34.50 0.09 | 34.14 -0.09 | 0.36
24 LAC Chris Kaman 17.00 | 32.83 -0.58 | 35.24 0.63 | -2.41
25 UTA Greg Ostertag 16.88 | 32.08 -0.84 | 35.62 0.93 | -3.54
26 POR Joel Przybilla 16.85 | 35.80 1.05 | 31.84 -0.93 | 3.97
27 UTA Carlos Boozer 16.82 | 31.96 -0.84 | 35.49 0.93 | -3.53
28 NOH Chris Andersen 16.56 | 31.99 -0.56 | 34.33 0.60 | -2.34
29 GSW Troy Murphy 16.46 | 33.79 0.43 | 32.10 -0.41 | 1.69
30 SEA Chris Wilcox 16.40 | 33.17 0.18 | 32.44 -0.18 | 0.7
I'll also post top 10 and bottom 10, across the league, for R23-diff, for whatever it's worth:
Code:
Tm Name R23-diff | Tm Name R23-diff
---------------------------------------------------------------------------------
1 POR Joel Przybilla 3.97 | 1 DAL Erick Dampier -3.84
2 CHA Emeka Okafor 3.50 | 2 MIA Shaquille O'Neal -3.66
3 POR Zach Randolph 3.29 | 3 UTA Greg Ostertag -3.54
4 PHO Kurt Thomas 3.05 | 4 UTA Carlos Boozer -3.53
5 PHO Shawn Marion 3.04 | 5 MIA Alonzo Mourning -3.36
6 POR Theo Ratliff 3.03 | 6 UTA Mehmet Okur -3.22
7 POR Viktor Khryapa 2.92 | 7 UTA Kris Humphries -3.21
8 CHA Jake Voskuhl 2.62 | 8 MIA Udonis Haslem -3.11
9 CHA Gerald Wallace 2.55 | 9 DAL DeSagana Diop -2.87
10 CHA Melvin Ely 2.41 | 10 DAL Dirk Nowitzki -2.7
Obviously, R23-diff is depenednt on how good/bad a rebounding team you're on. Not sure what insights (if any) can be taken from this.
Last edited by deepak on Fri Aug 11, 2006 10:49 am; edited 1 time in total
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HoopStudies
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PostPosted: Fri Aug 11, 2006 10:46 am Post subject: Reply with quote
admin wrote:
I dunno, Dean, that seems way too theoretical to me.
From a practical perspective, we accept that rebounding is not linear, correct?
By that I mean that if we know the rebound rates (I don't like that term, because scoring rate means per-40 minutes generally) of the five players on the floor, simply adding them together isn't totally sufficient to find the rebound rate of that unit.
In most cases, you can safely add them up, but when you have an extremely poor rebounder or an extremely good rebounder, that player is going to have less impact on his team than it appears from his rebound rate because he's not giving/taking away all of those rebounds from the other team; some are just a redistribution of rebounds his team would get already.
Do we accept that?
Not without evidence. I think many believe it, but let's see some evidence. And I'd believe it in general, but not necessarily in specific cases.
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Kevin Pelton
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PostPosted: Fri Aug 11, 2006 11:15 am Post subject: Reply with quote
What about Ed's post here? Doesn't that at least strongly imply that improved defensive rebounding by a player takes away some rebounds from teammates?
I remembered Ed's post in the shower and it implies that we probably should not adjust offensive rebounding for team context nearly so much as defensive rebounding.
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HoopStudies
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PostPosted: Fri Aug 11, 2006 11:26 am Post subject: Reply with quote
admin wrote:
What about Ed's post here? Doesn't that at least strongly imply that improved defensive rebounding by a player takes away some rebounds from teammates?
I remembered Ed's post in the shower and it implies that we probably should not adjust offensive rebounding for team context nearly so much as defensive rebounding.
Looks good to me and looks like the start of a way to have a stat for adjusting for context... And it would (probably) adjust McGrady's dreb% downward, which is what the original poster "felt".
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gabefarkas
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PostPosted: Fri Aug 11, 2006 11:32 am Post subject: Reply with quote
HoopStudies wrote:
That's the thing -- we don't know. A player getting a lot of rebounds on a bad rebounding team isn't necessarily better than a player getting the same amount on a good rebounding team. Because what is "better"? The whole reason this came up is because someone subjectively believed that Drexler was a better rebounder than McGrady. But why would anyone believe this up front? Just because Drexler was one of the top 50 of all time? "Better" is completely relative to some objective. Define your objective. Define "better".
Right now, we have overall rebound rate and rebound rate relative to the team. Does either reflect a "better" rebounder?
Well, before answering that (with my opinion), let me ask you: do you believe that under "ideal" conditions, each team should theoretically get 50% of all available rebounds?
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gabefarkas
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PostPosted: Fri Aug 11, 2006 11:44 am Post subject: Reply with quote
deepak_e wrote:
Obviously, R23-diff is depenednt on how good/bad a rebounding team you're on. Not sure what insights (if any) can be taken from this.
I don't think that's obvious.
R23-diff = (% of team's rebounds player got) - (% of opponent's rebounds player got)
So, this could possibly be used to determine how good a team was at rebounding, albeit in a roundabout way. I don't see what else it could clearly tell.
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HoopStudies
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PostPosted: Fri Aug 11, 2006 11:47 am Post subject: Reply with quote
gabefarkas wrote:
HoopStudies wrote:
That's the thing -- we don't know. A player getting a lot of rebounds on a bad rebounding team isn't necessarily better than a player getting the same amount on a good rebounding team. Because what is "better"? The whole reason this came up is because someone subjectively believed that Drexler was a better rebounder than McGrady. But why would anyone believe this up front? Just because Drexler was one of the top 50 of all time? "Better" is completely relative to some objective. Define your objective. Define "better".
Right now, we have overall rebound rate and rebound rate relative to the team. Does either reflect a "better" rebounder?
Well, before answering that (with my opinion), let me ask you: do you believe that under "ideal" conditions, each team should theoretically get 50% of all available rebounds?
I don't understand the question.
But what Ed did is define a relationship showing how individual rebounding impacts team rebounding. So, using his stuff can give a basis for defining a "better" rebounder -- one that more improves the team's rebounding. If other people have another basis in mind or, more practically, an implementation of his work to this question, it's fine to throw out there.
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deepak
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PostPosted: Fri Aug 11, 2006 2:46 pm Post subject: Reply with quote
I used the data at 82games.com to get the team rebounding% for all the top 5 man units for each team. Then I found how this correlates with the sum of the individual player's OReb-R, DReb-R, Reb-R, Reb2-R and Reb3-R which I'll call Oreb_sum, Dreb_sum, Reb_sum, Reb2_sum, and Reb3_sum respectively.
Correlation with TmReb%
top 20 units of each team:
Oreb_sum: 0.334
Dreb_sum: 0.142
Reb_sum: 0.280
Reb2_sum:0.229
Reb3_sum:0.285
top 10 units of each team:
Oreb_sum: 0.408
Dreb_sum: 0.165
Reb_sum: 0.337
Reb2_sum:0.258
Reb3_sum:0.363
top 5 units of each team:
Oreb_sum: 0.449
Dreb_sum: 0.164
Reb_sum: 0.355
Reb2_sum:0.225
Reb3_sum:0.351
Perhaps I'm out of my element trying to interpret what these correlations means ... but does it make sense that the sum of the player's OReb-rate would correlate better than the sum of the player's Reb-rate? I thought since Reb-rate included more information, it would be a better indicator. And it appears that DReb_sum has almost no relation to TmReb%.
These are the formulas I used for DReb-R and OReb-R. Maybe I messed up somewhere:
DReb-R = (DefReb * TmMin/5)/(min*(TmDReb + OppOReb))
OReb-R = (OffReb * TmMin/5)/(min*(TmOReb + OppDReb))
Reb2-R (percentage of team's rebounds player gets) doesn't seem to do very well. Reb3-R (percentage of opponent's rebounds player gets) does about as well as Reb-R.
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gabefarkas
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PostPosted: Sun Aug 13, 2006 1:04 pm Post subject: Reply with quote
HoopStudies wrote:
I don't understand the question.
But what Ed did is define a relationship showing how individual rebounding impacts team rebounding. So, using his stuff can give a basis for defining a "better" rebounder -- one that more improves the team's rebounding. If other people have another basis in mind or, more practically, an implementation of his work to this question, it's fine to throw out there.
Sure, let me try to explain. Let's assume that Team A puts five players on the floor, the sum of whose RbR's equal 50 (for argument's sake, each player's RbR can be 10, but it doesn't have to be). Then assume Team B does the same, fielding 5 players whose rebounding rates sum to 50. The implication here is that (a) each team is theoretically capable of grabbing 50% of available rebounds, and optionally (b) since there's 10 players on the floor each player is theoretically capable of grabbing 1/10th (10%) of available rebounds (although this is a stricter constraint).
Given that, would it be safe to conclude, forgetting what you know about stochastic processes, that each team will rebound 50% of the missed shots during a game?
If so, then RbR doesn't need to be subjected to all of this contextual analysis. If not, then I would want to conclude that a player's RbR is affected by whether he/she is on a good rebounding team or a bad rebounding team.
More simply, if Joel Pryzbilla is on Team A, and he's the only half-decent rebounder on the team, then his RbR will appear inflated because he's competing with less people for rebounds. Conversely, if Erick Dampier's teammates on Team B are good rebounders themselves, then his RbR might not reflect his true ability as a rebounder.
Does that make sense?
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HoopStudies
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PostPosted: Mon Aug 14, 2006 9:48 am Post subject: Reply with quote
gabefarkas wrote:
HoopStudies wrote:
I don't understand the question.
But what Ed did is define a relationship showing how individual rebounding impacts team rebounding. So, using his stuff can give a basis for defining a "better" rebounder -- one that more improves the team's rebounding. If other people have another basis in mind or, more practically, an implementation of his work to this question, it's fine to throw out there.
Sure, let me try to explain. Let's assume that Team A puts five players on the floor, the sum of whose RbR's equal 50 (for argument's sake, each player's RbR can be 10, but it doesn't have to be). Then assume Team B does the same, fielding 5 players whose rebounding rates sum to 50. The implication here is that (a) each team is theoretically capable of grabbing 50% of available rebounds, and optionally (b) since there's 10 players on the floor each player is theoretically capable of grabbing 1/10th (10%) of available rebounds (although this is a stricter constraint).
Given that, would it be safe to conclude, forgetting what you know about stochastic processes, that each team will rebound 50% of the missed shots during a game?
Well, that is the question at hand -- is it "safe" to conclude that? It is safe in the absence of other evidence. Ed provides some other evidence that suggests that it's "safer" to conclude that on the offensive end than on the defensive end.
gabefarkas wrote:
More simply, if Joel Pryzbilla is on Team A, and he's the only half-decent rebounder on the team, then his RbR will appear inflated because he's competing with less people for rebounds. Conversely, if Erick Dampier's teammates on Team B are good rebounders themselves, then his RbR might not reflect his true ability as a rebounder.
Ed's work suggests that his defensive boards may be "inflated", but perhaps not his offensive boards.
All this is, of course, just tendencies over a large statistical sample. A rule of thumb. For Przybilla or Dampier, it might be different. Knowing individual tendencies - rather than the group as a whole - is pretty important.
Nonetheless, the task remains undone -- adjusting offensive and defensive rebounding rates in a general way based on Ed's results. It's a worthwhile task.
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tsherkin
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PostPosted: Tue Aug 22, 2006 2:27 pm Post subject: Reply with quote
I have another question about rebounding rate; if you have a player's rebounding rate, how would you project what his actual rpg average might be? I guess you'd need pace data and such, right?
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tsherkin
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PostPosted: Wed Aug 09, 2006 2:15 pm Post subject: What's the value of Rebounding Rate? Reply with quote
What does it tell you?
I mean, obviously it gives you the percentage of available rebounds that a player pulled down but does it account for the quality of rebounders on your team?
I'm having a discussion with someone about Drexler versus T-Mac as a rebounder. Both of them have good peak RbR seasons but McGrady's actually had a couple of much higher RbR seasons. Does this reflect the abject lack of rebounders he usually experiences or is he just that much better a rebounder than Drexler?
Thanks!
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Chronz1
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PostPosted: Thu Aug 10, 2006 12:26 am Post subject: Reply with quote
Having a high rebound rate on a great rebounding team is more impressive than a slightly higher rating on horrible rebounding team.
Clydes rebound rate was consistantly around 9-10, even in his final days as a player with rebounding machines like Barkely and Hakeem around he was able to crash the boards at an effective rate.
Tmac has had some higher rebounding seasons but they were on squads where he was at times the best rebounder on the floor. But Id say they were close equals and you wouldnt gain much of an age by choosing either one of them. McGrady was the better defensive rebounder, but when Clyde wasnt shooting the ball he was hitting the glass alot more than Tmac does.
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deepak
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PostPosted: Thu Aug 10, 2006 12:31 am Post subject: Re: What's the value of Rebounding Rate? Reply with quote
tsherkin wrote:
What does it tell you?
I mean, obviously it gives you the percentage of available rebounds that a player pulled down but does it account for the quality of rebounders on your team?
As you say, it estimates the percentage of available rebounds a player pulls down. So, it doesn't take into account what the other teammates are doing on the boards.
Quote:
I'm having a discussion with someone about Drexler versus T-Mac as a rebounder. Both of them have good peak RbR seasons but McGrady's actually had a couple of much higher RbR seasons. Does this reflect the abject lack of rebounders he usually experiences or is he just that much better a rebounder than Drexler?
This is more a reflection of difference in position/role McGrady played, compared to Drexler. During McGrady's years in Toronto, I believe he was more a SF/PF then a SG/SF. He also averaged 2.1, 2.4, and 2.5 blocks per 40 minutes his first 3 seasons as well.
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tsherkin
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PostPosted: Thu Aug 10, 2006 12:33 am Post subject: Re: What's the value of Rebounding Rate? Reply with quote
Well, that's helpful, thanks for the answers, folks.
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gabefarkas
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PostPosted: Thu Aug 10, 2006 12:49 pm Post subject: Reply with quote
Maybe we need to come up with a RbR that compares a player's rebounds to just his teammates. Something similar to the established RbR, but only comparing to the total rebounds for a player's team, not all rebounds while he was on the floor.
That way, you could see if a guy is on a poor rebounding team and got 50% of his team's rebounds, vs if he was on a very good rebounding team and only got like 10% of his team's rebounds.
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tsherkin
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PostPosted: Thu Aug 10, 2006 1:53 pm Post subject: Reply with quote
gabefarkas wrote:
Maybe we need to come up with a RbR that compares a player's rebounds to just his teammates. Something similar to the established RbR, but only comparing to the total rebounds for a player's team, not all rebounds while he was on the floor.
That way, you could see if a guy is on a poor rebounding team and got 50% of his team's rebounds, vs if he was on a very good rebounding team and only got like 10% of his team's rebounds.
That'd be nice, some way of measuring/simulating a player's rebounding prowess on a good rebounding team. It'd be ideal for the comparison I was working with. But how would you do that?
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gabefarkas
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PostPosted: Thu Aug 10, 2006 3:41 pm Post subject: Reply with quote
tsherkin wrote:
That'd be nice, some way of measuring/simulating a player's rebounding prowess on a good rebounding team. It'd be ideal for the comparison I was working with. But how would you do that?
Well, if you have all the data to calculate RbR, I would think that the data needed to calculate what I suggested would be a subset of the RbR data, no?
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Eli W
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PostPosted: Thu Aug 10, 2006 4:22 pm Post subject: Reply with quote
You guys might be interested in Mike G and tomverve's take on a similar (though in some ways opposite) topic in this thread:
http://sonicscentral.com/apbrmetrics/vi ... .php?t=540
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tsherkin
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PostPosted: Thu Aug 10, 2006 9:30 pm Post subject: Reply with quote
gabefarkas wrote:
Well, if you have all the data to calculate RbR, I would think that the data needed to calculate what I suggested would be a subset of the RbR data, no?
So you're saying eliminate opponents rebounds from the equation?
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deepak
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PostPosted: Thu Aug 10, 2006 10:46 pm Post subject: Reply with quote
tsherkin wrote:
gabefarkas wrote:
Well, if you have all the data to calculate RbR, I would think that the data needed to calculate what I suggested would be a subset of the RbR data, no?
So you're saying eliminate opponents rebounds from the equation?
This is what I get, when I change (TmReb + OppReb) to just (TmReb) in the RebR equation. I'll call RebR the original formula, and RebR2 the newly proposed metric:
Code:
Tm Name RebR Tm Name RebR2
1 SEA/DEN Reggie Evans 21.46 1 SEA/DEN Reggie Evans 43.32
2 DEN Marcus Camby 21.05 2 DEN Marcus Camby 42.38
3 IND Jeff Foster 20.92 3 IND Jeff Foster 41.39
4 ORL Dwight Howard 20.85 4 ORL Dwight Howard 40.78
5 DAL Erick Dampier 19.96 5 MIN Kevin Garnett 40.08
6 HOU Chuck Hayes 19.65 6 HOU Chuck Hayes 38.94
7 MIN Kevin Garnett 19.58 7 CHI Tyson Chandler 38.22
8 CHI Tyson Chandler 19.35 8 DET Ben Wallace 38.18
9 DET Ben Wallace 19.01 9 DAL Erick Dampier 38.09
10 HOU Dikembe Mutombo 18.76 10 HOU Dikembe Mutombo 37.18
11 MIL Jamaal Magloire 18.74 11 PHI Samuel Dalembert 37.13
12 SAS Tim Duncan 18.68 12 MIL Jamaal Magloire 37.08
13 BOS Kendrick Perkins 18.44 13 BOS Kendrick Perkins 37.08
14 CLE Anderson Varejao 18.24 14 SAS Tim Duncan 36.84
15 CLE Drew Gooden 18.10 15 CHA Emeka Okafor 36.43
16 PHI Samuel Dalembert 17.99 16 POR Joel Przybilla 35.80
17 SAS Nazr Mohammed 17.77 17 MEM Jake Tsakalidis 35.70
18 MIA Shaquille O'Neal 17.63 18 CLE Anderson Varejao 35.20
19 MEM Jake Tsakalidis 17.53 19 MIN Eddie Griffin 35.13
20 HOU Yao Ming 17.50 20 SAS Nazr Mohammed 35.04
21 CHA Emeka Okafor 17.29 21 CLE Drew Gooden 34.93
22 MIN Eddie Griffin 17.16 22 HOU Yao Ming 34.68
23 BOS Al Jefferson 17.16 23 BOS Al Jefferson 34.50
24 LAC Chris Kaman 17.00 24 PHO Kurt Thomas 34.24
25 UTA Greg Ostertag 16.88 25 PHO Shawn Marion 34.16
26 POR Joel Przybilla 16.85 26 GSW Troy Murphy 33.79
27 UTA Carlos Boozer 16.82 27 MIA Shaquille O'Neal 33.52
28 NOH Chris Andersen 16.56 28 LAC Chris Kaman 32.8
Left columns is top 28 (minimum 500 MP), by RebR. Right column is top 28, by RebR2. As you can see, it's almost identical.
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Mike G
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PostPosted: Fri Aug 11, 2006 7:22 am Post subject: Reply with quote
In the above table, RebR2 only tells us what % of your team's rebounds you are getting. So getting 30% of the rebounds of the best-rebounding team doesn't rank you any higher than getting 30% of the worst-rebounding team's.
Going in the opposite direction -- measuring as a % of opponent rebounds -- gauges you against the rest of the league as a whole. This, to me, is the measure of how well you rebound. Otherwise, just list your team's Reb/40 or whatever.
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gabefarkas
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PostPosted: Fri Aug 11, 2006 8:49 am Post subject: Reply with quote
The biggest difference to me looks like Joel Pryzbilla. He's much higher on the RbR2 list. Could we then infer that his rebound numbers are inflated by being in a weak-rebounding team?
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gabefarkas
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PostPosted: Fri Aug 11, 2006 9:08 am Post subject: Reply with quote
So I'm trying to reconcile the two lists by doing this:
Combo = (RbR2 / 2) - (RbR)
I divide RbR2 by 2 with the assumption that if a team evenly rebounded its opponents, then Combo=0. This way, we can see guys who were genuinely good rebounders, versus guys who benefitted from being on poor rebounding teams.
There were 25 guys who were on both lists. If someone wants to provide the numbers for the missing guys, I can add them to the list.
Code:
Name RebR RebR2 Combo
Erick Dampier 19.96 38.09 -0.915
Shaquille O'Neal 17.63 33.52 -0.87
Anderson Varejao 18.24 35.2 -0.64
Drew Gooden 18.1 34.93 -0.635
Chris Kaman 17 32.8 -0.6
Dwight Howard 20.85 40.78 -0.46
Tim Duncan 18.68 36.84 -0.26
Nazr Mohammed 17.77 35.04 -0.25
Tyson Chandler 19.35 38.22 -0.24
Jeff Foster 20.92 41.39 -0.225
Jamaal Magloire 18.74 37.08 -0.2
Chuck Hayes 19.65 38.94 -0.18
Dikembe Mutombo 18.76 37.18 -0.17
Yao Ming 17.5 34.68 -0.16
Ben Wallace 19.01 38.18 0.08
Al Jefferson 17.16 34.5 0.09
Kendrick Perkins 18.44 37.08 0.1
Marcus Camby 21.05 42.38 0.14
Reggie Evans 21.46 43.32 0.2
Jake Tsakalidis 17.53 35.7 0.32
Eddie Griffin 17.16 35.13 0.405
Kevin Garnett 19.58 40.08 0.46
Samuel Dalembert 17.99 37.13 0.575
Emeka Okafor 17.29 36.43 0.925
Joel Przybilla 16.85 35.8 1.05
The way I interpret it is like this: Joel Pryzbilla benefitted from being on a weak rebounding team, thus grabbing more rebounds than his teammates otherwise might have. On the other hand, Erick Dampier was on a strong rebounding team, so his personal rebounding numbers are inflated.
Maybe I have that backwards?
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HoopStudies
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PostPosted: Fri Aug 11, 2006 9:40 am Post subject: Reply with quote
gabefarkas wrote:
The way I interpret it is like this: Joel Pryzbilla benefitted from being on a weak rebounding team, thus grabbing more rebounds than his teammates otherwise might have. On the other hand, Erick Dampier was on a strong rebounding team, so his personal rebounding numbers are inflated.
Maybe I have that backwards?
That's the thing -- we don't know. A player getting a lot of rebounds on a bad rebounding team isn't necessarily better than a player getting the same amount on a good rebounding team. Because what is "better"? The whole reason this came up is because someone subjectively believed that Drexler was a better rebounder than McGrady. But why would anyone believe this up front? Just because Drexler was one of the top 50 of all time? "Better" is completely relative to some objective. Define your objective. Define "better".
Right now, we have overall rebound rate and rebound rate relative to the team. Does either reflect a "better" rebounder?
Note that we have this same problem with the passing rating of some other thread. We don't know what "better" is, so it's hard to evaluate such a thing. Or if we wanted a "better" shooter, what is that? These reflect measures we HAVE stats for. It's a matter of defining what makes "better", doing the analysis relative to some objective. This is as opposed to defense, where the stats are so limited that defining what makes "better" is harder.
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Kevin Pelton
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PostPosted: Fri Aug 11, 2006 10:00 am Post subject: Reply with quote
I dunno, Dean, that seems way too theoretical to me.
From a practical perspective, we accept that rebounding is not linear, correct?
By that I mean that if we know the rebound rates (I don't like that term, because scoring rate means per-40 minutes generally) of the five players on the floor, simply adding them together isn't totally sufficient to find the rebound rate of that unit.
In most cases, you can safely add them up, but when you have an extremely poor rebounder or an extremely good rebounder, that player is going to have less impact on his team than it appears from his rebound rate because he's not giving/taking away all of those rebounds from the other team; some are just a redistribution of rebounds his team would get already.
Do we accept that?
Now, that being said, just looking at a team's opponents' rebounds seems to be a crude and subjective adjustment given we haven't really studied this issue in much detail and I don't think it matters much except at the extremes.
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tsherkin
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PostPosted: Fri Aug 11, 2006 10:05 am Post subject: Reply with quote
As far as "better" meant in my original question, someone was wondering if McGrady's rebounding numbers were merely because Orlando sucked and how important it was that Drexler played on good rebounding teams (in a faster-paced era).
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deepak
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PostPosted: Fri Aug 11, 2006 10:30 am Post subject: Reply with quote
The following table shows top 30, by rebound rate, as well as a few other metrics that might be of interest in this discussion.
Reb-R2: % of team's rebounds player got
R2-diff : Reb-R2/2 - Reb-R
Reb-R3: % of opponent's rebounds player got (as per Mike's suggestion)
R3-diff: Reb-R3/2 - Reb-R
R23-diff: Reb-R2 - Reb-R3
Code:
Tm Name Reb-R | Reb-R2 R2-diff | Reb-R3 R3-diff | R23-diff
----------------------------------------------------------------------------------------------
1 SEA/DEN Reggie Evans 21.79 | 44.06 0.24 | 43.09 -0.24 | 0.97
2 DEN Marcus Camby 21.05 | 42.38 0.14 | 41.82 -0.14 | 0.56
3 IND Jeff Foster 20.92 | 41.39 -0.22 | 42.28 0.23 | -0.89
4 ORL Dwight Howard 20.85 | 40.78 -0.46 | 42.64 0.48 | -1.86
5 DAL Erick Dampier 19.96 | 38.09 -0.91 | 41.94 1.01 | -3.84
6 HOU Chuck Hayes 19.65 | 38.94 -0.18 | 39.67 0.18 | -0.73
7 MIN Kevin Garnett 19.58 | 40.08 0.46 | 38.28 -0.44 | 1.80
8 CHI Tyson Chandler 19.35 | 38.22 -0.24 | 39.18 0.24 | -0.96
9 DET Ben Wallace 19.01 | 38.18 0.08 | 37.86 -0.08 | 0.32
10 HOU Dikembe Mutombo 18.76 | 37.18 -0.17 | 37.88 0.18 | -0.70
11 MIL Jamaal Magloire 18.74 | 37.08 -0.19 | 37.87 0.20 | -0.78
12 SAS Tim Duncan 18.68 | 36.84 -0.26 | 37.91 0.27 | -1.07
13 BOS Kendrick Perkins 18.44 | 37.08 0.10 | 36.69 -0.10 | 0.38
14 CLE Anderson Varejao 18.24 | 35.20 -0.64 | 37.84 0.68 | -2.64
15 CLE Drew Gooden 18.10 | 34.93 -0.63 | 37.55 0.68 | -2.62
16 PHI Samuel Dalembert 17.99 | 37.13 0.57 | 34.91 -0.54 | 2.21
17 SAS Nazr Mohammed 17.77 | 35.04 -0.25 | 36.06 0.26 | -1.02
18 MIA Shaquille O'Neal 17.63 | 33.52 -0.87 | 37.18 0.96 | -3.66
19 MEM Jake Tsakalidis 17.53 | 35.70 0.32 | 34.44 -0.31 | 1.26
20 HOU Yao Ming 17.50 | 34.68 -0.16 | 35.34 0.16 | -0.65
21 CHA Emeka Okafor 17.29 | 36.43 0.92 | 32.92 -0.83 | 3.50
22 MIN Eddie Griffin 17.16 | 35.13 0.40 | 33.55 -0.39 | 1.58
23 BOS Al Jefferson 17.16 | 34.50 0.09 | 34.14 -0.09 | 0.36
24 LAC Chris Kaman 17.00 | 32.83 -0.58 | 35.24 0.63 | -2.41
25 UTA Greg Ostertag 16.88 | 32.08 -0.84 | 35.62 0.93 | -3.54
26 POR Joel Przybilla 16.85 | 35.80 1.05 | 31.84 -0.93 | 3.97
27 UTA Carlos Boozer 16.82 | 31.96 -0.84 | 35.49 0.93 | -3.53
28 NOH Chris Andersen 16.56 | 31.99 -0.56 | 34.33 0.60 | -2.34
29 GSW Troy Murphy 16.46 | 33.79 0.43 | 32.10 -0.41 | 1.69
30 SEA Chris Wilcox 16.40 | 33.17 0.18 | 32.44 -0.18 | 0.7
I'll also post top 10 and bottom 10, across the league, for R23-diff, for whatever it's worth:
Code:
Tm Name R23-diff | Tm Name R23-diff
---------------------------------------------------------------------------------
1 POR Joel Przybilla 3.97 | 1 DAL Erick Dampier -3.84
2 CHA Emeka Okafor 3.50 | 2 MIA Shaquille O'Neal -3.66
3 POR Zach Randolph 3.29 | 3 UTA Greg Ostertag -3.54
4 PHO Kurt Thomas 3.05 | 4 UTA Carlos Boozer -3.53
5 PHO Shawn Marion 3.04 | 5 MIA Alonzo Mourning -3.36
6 POR Theo Ratliff 3.03 | 6 UTA Mehmet Okur -3.22
7 POR Viktor Khryapa 2.92 | 7 UTA Kris Humphries -3.21
8 CHA Jake Voskuhl 2.62 | 8 MIA Udonis Haslem -3.11
9 CHA Gerald Wallace 2.55 | 9 DAL DeSagana Diop -2.87
10 CHA Melvin Ely 2.41 | 10 DAL Dirk Nowitzki -2.7
Obviously, R23-diff is depenednt on how good/bad a rebounding team you're on. Not sure what insights (if any) can be taken from this.
Last edited by deepak on Fri Aug 11, 2006 10:49 am; edited 1 time in total
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HoopStudies
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PostPosted: Fri Aug 11, 2006 10:46 am Post subject: Reply with quote
admin wrote:
I dunno, Dean, that seems way too theoretical to me.
From a practical perspective, we accept that rebounding is not linear, correct?
By that I mean that if we know the rebound rates (I don't like that term, because scoring rate means per-40 minutes generally) of the five players on the floor, simply adding them together isn't totally sufficient to find the rebound rate of that unit.
In most cases, you can safely add them up, but when you have an extremely poor rebounder or an extremely good rebounder, that player is going to have less impact on his team than it appears from his rebound rate because he's not giving/taking away all of those rebounds from the other team; some are just a redistribution of rebounds his team would get already.
Do we accept that?
Not without evidence. I think many believe it, but let's see some evidence. And I'd believe it in general, but not necessarily in specific cases.
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Kevin Pelton
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PostPosted: Fri Aug 11, 2006 11:15 am Post subject: Reply with quote
What about Ed's post here? Doesn't that at least strongly imply that improved defensive rebounding by a player takes away some rebounds from teammates?
I remembered Ed's post in the shower and it implies that we probably should not adjust offensive rebounding for team context nearly so much as defensive rebounding.
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HoopStudies
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PostPosted: Fri Aug 11, 2006 11:26 am Post subject: Reply with quote
admin wrote:
What about Ed's post here? Doesn't that at least strongly imply that improved defensive rebounding by a player takes away some rebounds from teammates?
I remembered Ed's post in the shower and it implies that we probably should not adjust offensive rebounding for team context nearly so much as defensive rebounding.
Looks good to me and looks like the start of a way to have a stat for adjusting for context... And it would (probably) adjust McGrady's dreb% downward, which is what the original poster "felt".
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gabefarkas
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PostPosted: Fri Aug 11, 2006 11:32 am Post subject: Reply with quote
HoopStudies wrote:
That's the thing -- we don't know. A player getting a lot of rebounds on a bad rebounding team isn't necessarily better than a player getting the same amount on a good rebounding team. Because what is "better"? The whole reason this came up is because someone subjectively believed that Drexler was a better rebounder than McGrady. But why would anyone believe this up front? Just because Drexler was one of the top 50 of all time? "Better" is completely relative to some objective. Define your objective. Define "better".
Right now, we have overall rebound rate and rebound rate relative to the team. Does either reflect a "better" rebounder?
Well, before answering that (with my opinion), let me ask you: do you believe that under "ideal" conditions, each team should theoretically get 50% of all available rebounds?
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gabefarkas
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PostPosted: Fri Aug 11, 2006 11:44 am Post subject: Reply with quote
deepak_e wrote:
Obviously, R23-diff is depenednt on how good/bad a rebounding team you're on. Not sure what insights (if any) can be taken from this.
I don't think that's obvious.
R23-diff = (% of team's rebounds player got) - (% of opponent's rebounds player got)
So, this could possibly be used to determine how good a team was at rebounding, albeit in a roundabout way. I don't see what else it could clearly tell.
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HoopStudies
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PostPosted: Fri Aug 11, 2006 11:47 am Post subject: Reply with quote
gabefarkas wrote:
HoopStudies wrote:
That's the thing -- we don't know. A player getting a lot of rebounds on a bad rebounding team isn't necessarily better than a player getting the same amount on a good rebounding team. Because what is "better"? The whole reason this came up is because someone subjectively believed that Drexler was a better rebounder than McGrady. But why would anyone believe this up front? Just because Drexler was one of the top 50 of all time? "Better" is completely relative to some objective. Define your objective. Define "better".
Right now, we have overall rebound rate and rebound rate relative to the team. Does either reflect a "better" rebounder?
Well, before answering that (with my opinion), let me ask you: do you believe that under "ideal" conditions, each team should theoretically get 50% of all available rebounds?
I don't understand the question.
But what Ed did is define a relationship showing how individual rebounding impacts team rebounding. So, using his stuff can give a basis for defining a "better" rebounder -- one that more improves the team's rebounding. If other people have another basis in mind or, more practically, an implementation of his work to this question, it's fine to throw out there.
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deepak
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PostPosted: Fri Aug 11, 2006 2:46 pm Post subject: Reply with quote
I used the data at 82games.com to get the team rebounding% for all the top 5 man units for each team. Then I found how this correlates with the sum of the individual player's OReb-R, DReb-R, Reb-R, Reb2-R and Reb3-R which I'll call Oreb_sum, Dreb_sum, Reb_sum, Reb2_sum, and Reb3_sum respectively.
Correlation with TmReb%
top 20 units of each team:
Oreb_sum: 0.334
Dreb_sum: 0.142
Reb_sum: 0.280
Reb2_sum:0.229
Reb3_sum:0.285
top 10 units of each team:
Oreb_sum: 0.408
Dreb_sum: 0.165
Reb_sum: 0.337
Reb2_sum:0.258
Reb3_sum:0.363
top 5 units of each team:
Oreb_sum: 0.449
Dreb_sum: 0.164
Reb_sum: 0.355
Reb2_sum:0.225
Reb3_sum:0.351
Perhaps I'm out of my element trying to interpret what these correlations means ... but does it make sense that the sum of the player's OReb-rate would correlate better than the sum of the player's Reb-rate? I thought since Reb-rate included more information, it would be a better indicator. And it appears that DReb_sum has almost no relation to TmReb%.
These are the formulas I used for DReb-R and OReb-R. Maybe I messed up somewhere:
DReb-R = (DefReb * TmMin/5)/(min*(TmDReb + OppOReb))
OReb-R = (OffReb * TmMin/5)/(min*(TmOReb + OppDReb))
Reb2-R (percentage of team's rebounds player gets) doesn't seem to do very well. Reb3-R (percentage of opponent's rebounds player gets) does about as well as Reb-R.
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gabefarkas
Joined: 31 Dec 2004
Posts: 1313
Location: Durham, NC
PostPosted: Sun Aug 13, 2006 1:04 pm Post subject: Reply with quote
HoopStudies wrote:
I don't understand the question.
But what Ed did is define a relationship showing how individual rebounding impacts team rebounding. So, using his stuff can give a basis for defining a "better" rebounder -- one that more improves the team's rebounding. If other people have another basis in mind or, more practically, an implementation of his work to this question, it's fine to throw out there.
Sure, let me try to explain. Let's assume that Team A puts five players on the floor, the sum of whose RbR's equal 50 (for argument's sake, each player's RbR can be 10, but it doesn't have to be). Then assume Team B does the same, fielding 5 players whose rebounding rates sum to 50. The implication here is that (a) each team is theoretically capable of grabbing 50% of available rebounds, and optionally (b) since there's 10 players on the floor each player is theoretically capable of grabbing 1/10th (10%) of available rebounds (although this is a stricter constraint).
Given that, would it be safe to conclude, forgetting what you know about stochastic processes, that each team will rebound 50% of the missed shots during a game?
If so, then RbR doesn't need to be subjected to all of this contextual analysis. If not, then I would want to conclude that a player's RbR is affected by whether he/she is on a good rebounding team or a bad rebounding team.
More simply, if Joel Pryzbilla is on Team A, and he's the only half-decent rebounder on the team, then his RbR will appear inflated because he's competing with less people for rebounds. Conversely, if Erick Dampier's teammates on Team B are good rebounders themselves, then his RbR might not reflect his true ability as a rebounder.
Does that make sense?
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HoopStudies
Joined: 30 Dec 2004
Posts: 705
Location: Near Philadelphia, PA
PostPosted: Mon Aug 14, 2006 9:48 am Post subject: Reply with quote
gabefarkas wrote:
HoopStudies wrote:
I don't understand the question.
But what Ed did is define a relationship showing how individual rebounding impacts team rebounding. So, using his stuff can give a basis for defining a "better" rebounder -- one that more improves the team's rebounding. If other people have another basis in mind or, more practically, an implementation of his work to this question, it's fine to throw out there.
Sure, let me try to explain. Let's assume that Team A puts five players on the floor, the sum of whose RbR's equal 50 (for argument's sake, each player's RbR can be 10, but it doesn't have to be). Then assume Team B does the same, fielding 5 players whose rebounding rates sum to 50. The implication here is that (a) each team is theoretically capable of grabbing 50% of available rebounds, and optionally (b) since there's 10 players on the floor each player is theoretically capable of grabbing 1/10th (10%) of available rebounds (although this is a stricter constraint).
Given that, would it be safe to conclude, forgetting what you know about stochastic processes, that each team will rebound 50% of the missed shots during a game?
Well, that is the question at hand -- is it "safe" to conclude that? It is safe in the absence of other evidence. Ed provides some other evidence that suggests that it's "safer" to conclude that on the offensive end than on the defensive end.
gabefarkas wrote:
More simply, if Joel Pryzbilla is on Team A, and he's the only half-decent rebounder on the team, then his RbR will appear inflated because he's competing with less people for rebounds. Conversely, if Erick Dampier's teammates on Team B are good rebounders themselves, then his RbR might not reflect his true ability as a rebounder.
Ed's work suggests that his defensive boards may be "inflated", but perhaps not his offensive boards.
All this is, of course, just tendencies over a large statistical sample. A rule of thumb. For Przybilla or Dampier, it might be different. Knowing individual tendencies - rather than the group as a whole - is pretty important.
Nonetheless, the task remains undone -- adjusting offensive and defensive rebounding rates in a general way based on Ed's results. It's a worthwhile task.
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tsherkin
Joined: 31 Jan 2005
Posts: 247
PostPosted: Tue Aug 22, 2006 2:27 pm Post subject: Reply with quote
I have another question about rebounding rate; if you have a player's rebounding rate, how would you project what his actual rpg average might be? I guess you'd need pace data and such, right?