DSMok1
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PostPosted: Fri Mar 26, 2010 1:30 pm Post subject: Adjusting Assists Reply with quote
Tom Haberstroh had an excellent article over at Hardwood Paroxysm a few days ago about "Dismantling the Assist". The basic concept was to look at each player's assists and to value them based on how much better an assisted shot from that range was than an unassisted shot.
This struck me as the wrong way to approach it. I believe the better way to attack it is to compare the value of the shot from that location to a generic unassisted shot. For dunks in particular, this makes a huge difference.
The groundwork for all this comes from 82games.com's "The Value of a Good Pass". From there it is possible to see how much value an assist at each location is worth. Unfortunately, these bins don't match the HoopData location tables for assists. I therefore had to do some math to approximate how many assists of each type were represented in the HoopData table. Approximately: 33% of "At Rim" assists were dunks (the rest were "Close Shots"), and 50% of "<10 feet" assists were "Close Shots" (the rest were 2pt Jumpers in 82Games.com parlance).
An unassisted shot has an EFG% of approximately 44% (from what I calculated). To value the assists, then: compare the potential assists' EFG% to the 44% baseline.
The new point value for potential assists to each area:
Dunk: 0.960 pts
Close Shots: 0.346 pts
2 Pt. Jumper: 0.036 pts
3 Pt. Jumper: 0.257 pts
I then summed the points added and normalized so the new, tweaked "assists" still sum to the same total across the NBA. Basically, 1 point added = 2 assists.
So here are the new, adjusted assist leaders (Ast+ is a HoopData metric; my new metric is the "Adj. Assists") (stats per 40 min, NOT pace adjusted):
Code:
# Player Assists Ast+ Total Pts Adj. Assists Change (from Assists)
1 Steve Nash 13.4 15.0 7.0 14.0 0.6
2 Deron Williams 11.2 12.2 5.6 11.1 -0.1
3 Chris Paul 11.4 13.0 5.5 11.0 -0.4
4 Rajon Rondo 10.6 11.8 5.4 10.8 0.2
5 LeBron James 8.8 10.1 5.0 10.0 1.2
6 Baron Davis 9.4 10.2 4.7 9.4 0.0
7 Jameer Nelson 7.4 8.9 4.5 8.9 1.5
8 Russell Westbrook 9.1 10.1 4.4 8.7 -0.4
9 Jason Kidd 10.2 10.9 4.3 8.5 -1.7
10 Jose Calderon 8.6 9.6 4.1 8.2 -0.4
11 Darren Collison 8.3 9.4 4.0 7.9 -0.4
12 Devin Harris 7.7 8.3 3.9 7.8 0.1
13 Chris Duhon 7.4 8.5 3.9 7.8 0.4
14 Raymond Felton 6.5 7.4 3.8 7.5 1.0
15 Brandon Jennings 7.2 8.3 3.7 7.4 0.2
16 Gilbert Arenas 7.8 8.5 3.7 7.3 -0.5
17 Dwyane Wade 7.3 8.4 3.6 7.2 -0.1
18 Earl Watson 6.6 7.8 3.5 7.0 0.4
19 Tony Parker 7.2 8.4 3.5 7.0 -0.2
20 Manu Ginobili 6.9 7.6 3.5 7.0 0.1
21 Mike Conley 6.7 7.3 3.5 6.9 0.2
22 Andre Miller 7.1 8.0 3.4 6.8 -0.3
23 Mo Williams 5.9 6.4 3.4 6.7 0.8
24 Will Bynum 7.2 8.2 3.4 6.7 -0.5
25 Chauncey Billups 6.8 7.6 3.3 6.6 -0.2
26 T.J. Ford 6.1 7.1 3.2 6.4 0.3
27 Jarrett Jack 7.1 7.8 3.2 6.4 -0.7
28 Stephen Curry 6.2 6.9 3.2 6.3 0.1
29 Aaron Brooks 5.7 6.5 3.1 6.1 0.4
30 Larry Hughes 5.3 5.9 3.0 6.0 0.7
EDIT: I just found that Tom had an older post that looked at things more similarly to this (except without using the 44% baseline or using actual ASSISTED FG% for each location). Here that is:
http://www.hardwoodparoxysm.com/2010/03 ... w-assists/.
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habetw4
Joined: 12 Nov 2009
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PostPosted: Fri Mar 26, 2010 2:09 pm Post subject: Reply with quote
I don't mean to reinvent the assist statistic because I don't think we have enough granular data, at least publicly, to do the makeover. The two articles were more of an exploration of various ways to record an assist and how that reflects the player's value as a ball distributor. There are many ways to look at the value of the assist. I hope the 82games study and two pieces gets us closer to finding the answer.
The issue essentially boils down to the chicken or the egg problem. Does the passer create the open shots for the offense or does the offense create open shots for the passer? More to the point, should we discount, says, Jason Kidd's assists because his personnel/system environment lends itself to mid range shots, which, in general, are the least efficient shots in the game? Of course not. But then again, we'd like to reward players for opening up opportunities for teammates to get higher percentage shots that they wouldn't have normally received. This is where point expectancy comes in. That, I think, is the ultimate piece to the puzzle.
Like in all player evaluation, we want to assign credit where credit is due. The contextual factor of assists creates a host of misattribution errors that makes player evaluation more difficult. At this point, I think the answer is a blend of different metrics (on/off court, player pairs, type of assist breakdowns, etc) before we are able to delve into point expectancy.
Sometimes, I think assist as a statistic is so flawed it isn't worth the effort and time. But then I feel as though I'm missing an opportunity to find inefficiencies if I ignore them all together.
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DSMok1
Joined: 05 Aug 2009
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PostPosted: Fri Mar 26, 2010 2:27 pm Post subject: Reply with quote
habetw4 wrote:
I don't mean to reinvent the assist statistic because I don't think we have enough granular data, at least publicly, to do the makeover. The two articles were more of an exploration of various ways to record an assist and how that reflects the player's value as a ball distributor. There are many ways to look at the value of the assist. I hope the 82games study and two pieces gets us closer to finding the answer.
The issue essentially boils down to the chicken or the egg problem. Does the passer create the open shots for the offense or does the offense create open shots for the passer? More to the point, should we discount, says, Jason Kidd's assists because his personnel/system environment lends itself to mid range shots, which, in general, are the least efficient shots in the game? Of course not. But then again, we'd like to reward players for opening up opportunities for teammates to get higher percentage shots that they wouldn't have normally received. This is where point expectancy comes in. That, I think, is the ultimate piece to the puzzle.
Like in all player evaluation, we want to assign credit where credit is due. The contextual factor of assists creates a host of misattribution errors that makes player evaluation more difficult. At this point, I think the answer is a blend of different metrics (on/off court, player pairs, type of assist breakdowns, etc) before we are able to delve into point expectancy.
Sometimes, I think assist as a statistic is so flawed it isn't worth the effort and time. But then I feel as though I'm missing an opportunity to find inefficiencies if I ignore them all together.
I see what you were trying to do--more exploration than anything.
I would say that the assist is definitely a valid measure; there is a reason it is quite significant in the SPM regression. It does measure a player's impact in a certain dimension.
As for my version of "assists" and Jason Kidd: it appears that the best valuation would be somewhere in between pure assists (a success metric) vs. my adjusted assist (an efficiency metric). Similar to the difference between yards/carry in football and FirstDowns/carry. One measures "success"; the other "efficiency". True value is a synthesis of the two.
I suspect that using an adjusted version of assists such as this would allow a stronger correlation when doing an SPM-on-APM regression.
A few notable players that increased or decreased on this list:
Code:
Player Assists Adj. Ast. Change (from Assists)
Jameer Nelson 7.4 8.9 1.5
LeBron James 8.8 10.0 1.2
Raymond Felton 6.5 7.5 1.0
Mo Williams 5.9 6.7 0.8
Vince Carter 3.9 4.7 0.8
Larry Hughes 5.3 6.0 0.7
Stephen Jackson 3.7 4.4 0.7
Carmelo Anthony 3.6 4.3 0.7
Kevin Garnett 3.6 4.3 0.7
Steve Nash 13.4 14.0 0.6
Player Assists Adj. Ast. Change (from Assists)
Jason Kidd 10.2 8.5 -1.7
Kirk Hinrich 5.5 4.3 -1.2
Tayshaun Prince 3.4 2.2 -1.2
Derrick Rose 6.4 5.5 -0.9
Rafer Alston 5.4 4.6 -0.8
Rodney Stuckey 5.6 4.9 -0.7
Jarrett Jack 7.1 6.4 -0.7
Mike Miller 4.5 3.8 -0.7
Rafer Alston 4.4 3.8 -0.6
John Salmons 2.9 2.3 -0.6
Interesting!
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erivera7
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PostPosted: Sat Mar 27, 2010 4:28 pm Post subject: Reply with quote
I like the idea of the "adjusted assist" ... that's certainly one metric, in theory, that could be effectively used to find out who really is a good passer vis-a-vis the shots he creates for his teammates. The assist is a flawed statistic but I don't see why it can't be improved upon so it better captures what people are looking for.
I like what I see from the list provided above, so far.
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John Hollinger
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PostPosted: Tue Mar 30, 2010 11:09 am Post subject: Reply with quote
I think Tom just hit upon something very important which is why I've restrained myself from doing more in ratings to reflect 'assist quality' -- Jameer Nelson has about a hundred times more opportunity to make a pass leading to a dunk than Jason Kidd, simply because of who he plays with. (ok, slight exaggeration). If Jameer played with Caron Butler and Dirk while Kidd playe dwiht Dwight Howard I suspect the numbers would flip.
An interesting case study for the chicken-egg proposition would be to look at Nash in the two MVP years -- one with Amare, one without. Suspect he was setting up a lot more long Js the second year.
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Ryan J. Parker
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PostPosted: Tue Mar 30, 2010 11:13 am Post subject: Reply with quote
I think Dean makes a good argument for how to value assist quality in BoP. This is one of the many things I lose sleep over (think impact on usage), but in general I think it's a good way of attacking the problem.
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habetw4
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PostPosted: Tue Mar 30, 2010 11:35 am Post subject: Reply with quote
Quote:
I think Dean makes a good argument for how to value assist quality in BoP. This is one of the many things I lose sleep over (think impact on usage), but in general I think it's a good way of attacking the problem.
His discussion in BoP was the inspiration for my assist analysis. IIRC, at its core it is a point expectancy argument. The greater the change in point expectancy, the more credit we assign to the passer. We don't have the luxury of within-play point expectancy so a lot of assumptions would have to be made.
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DSMok1
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PostPosted: Tue Mar 30, 2010 11:55 am Post subject: Reply with quote
Good discussion, guys.
I thought my initial evaluation wasn't granular enough, so I went back and calculated an approximate unassisted and assisted FG% for each team at each location range. Estimating the overall unassisted FG% for each team gave me a baseline for each assist to each bin for each team. Now, Jason Kidd gets more credit for midrange assists; Nelson no longer gets overwhelming credit for dishing the ball to Howard.
A bye-product of this approach is that good passers on bad teams get adjusted upwards because of all the potential assists that were missed by their poor-shooting teammates. Devin Harris and Rip Hamilton are the biggest beneficiaries of this adjustment--both of their teams are about 41% estimated unassisted EFG%.
Until we know true unassisted FG% and assisted FG% for each range for each team, though, this will still just be an estimate. Perhaps Kidd's dishes to the midrange make a huge difference in Dirk's FG% for that range... maybe...
The new top 20:
Code:
Player Assists Ast+ Total Pts Adj. Ast. Change (from Assists)
Steve Nash 13.4 15.0 5.3 13.5 0.1
Chris Paul 11.4 13.0 4.4 11.1 -0.3
Deron Williams 11.2 12.2 4.1 10.4 -0.8
LeBron James 8.8 10.1 3.9 10.0 1.2
Rajon Rondo 10.6 11.8 3.8 9.7 -0.9
Baron Davis 9.4 10.2 3.8 9.6 0.2
Jason Kidd 10.2 10.9 3.7 9.4 -0.8
Devin Harris 7.7 8.3 3.5 8.8 1.1
Russell Westbrook 9.1 10.1 3.4 8.6 -0.5
Gilbert Arenas 7.8 8.5 3.4 8.5 0.7
Brandon Jennings 7.2 8.3 3.3 8.3 1.1
Jose Calderon 8.6 9.6 3.3 8.3 -0.3
Darren Collison 8.3 9.4 3.2 8.0 -0.3
Jameer Nelson 7.4 8.9 3.0 7.7 0.3
Dwyane Wade 7.3 8.4 3.0 7.6 0.3
Raymond Felton 6.5 7.4 2.9 7.3 0.8
Andre Miller 7.1 8.0 2.8 7.0 -0.1
Earl Watson 6.6 7.8 2.7 7.0 0.4
Manu Ginobili 6.9 7.6 2.7 6.9 0.0
Mike Conley 6.7 7.3 2.7 6.8 0.1
And the new "biggest movers":
Code:
Player Assists Ast+ Total Pts Adj. Ast. Change (from Assists)
LeBron James 8.8 10.1 3.9 10.0 1.2
Richard Hamilton 5.1 5.5 2.5 6.2 1.1
Brandon Jennings 7.2 8.3 3.3 8.3 1.1
Devin Harris 7.7 8.3 3.5 8.8 1.1
Raymond Felton 6.5 7.4 2.9 7.3 0.8
Carmelo Anthony 3.6 4.0 1.7 4.4 0.8
Andrew Bogut 2.4 2.8 1.3 3.2 0.8
Stephen Jackson 3.7 4.0 1.8 4.5 0.8
Mo Williams 5.9 6.4 2.6 6.7 0.8
Lou Williams 5.3 5.8 2.4 6.1 0.8
Kevin Garnett 3.6 4.1 1.7 4.3 0.7
Gilbert Arenas 7.8 8.5 3.4 8.5 0.7
Andray Blatche 2.5 2.8 1.2 3.2 0.7
Josh Smith 4.9 5.6 2.2 5.5 0.6
Andre Iguodala 5.8 6.3 2.5 6.4 0.6
Player Assists Ast+ Total Pts Adj. Ast. Change (from Assists)
Chauncey Billups 6.8 7.6 2.4 6.2 -0.6
Mehmet Okur 2.4 2.5 0.7 1.8 -0.6
Boris Diaw 4.3 4.9 1.4 3.7 -0.6
Beno Udrih 5.7 6.3 2.0 5.0 -0.7
Derrick Rose 6.4 7.1 2.3 5.7 -0.7
Kirk Hinrich 5.5 5.8 1.9 4.8 -0.7
Tony Parker 7.2 8.4 2.5 6.4 -0.8
Tyreke Evans 6.0 6.9 2.1 5.2 -0.8
Jarrett Jack 7.1 7.8 2.5 6.3 -0.8
Jason Kidd 10.2 10.9 3.7 9.4 -0.8
George Hill 3.8 4.3 1.2 3.0 -0.8
Deron Williams 11.2 12.2 4.1 10.4 -0.8
Rajon Rondo 10.6 11.8 3.8 9.7 -0.9
Paul Pierce 3.7 4.0 1.1 2.8 -0.9
Tayshaun Prince 3.4 3.8 0.9 2.3 -1.1
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Ryan J. Parker
Joined: 23 Mar 2007
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PostPosted: Tue Mar 30, 2010 12:37 pm Post subject: Reply with quote
habetw4 wrote:
Quote:
I think Dean makes a good argument for how to value assist quality in BoP. This is one of the many things I lose sleep over (think impact on usage), but in general I think it's a good way of attacking the problem.
His discussion in BoP was the inspiration for my assist analysis. IIRC, at its core it is a point expectancy argument. The greater the change in point expectancy, the more credit we assign to the passer. We don't have the luxury of within-play point expectancy so a lot of assumptions would have to be made.
Yeah I knew you were doing this, just wanted to point that out to JH Cool
Ultimately he's right in that assist totals aren't that useful, even if you do adjust them.
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Roland_Beech
Joined: 14 Jan 2005
Posts: 43
PostPosted: Thu Apr 01, 2010 6:12 pm Post subject: Reply with quote
John Hollinger wrote:
An interesting case study for the chicken-egg proposition would be to look at Nash in the two MVP years -- one with Amare, one without. Suspect he was setting up a lot more long Js the second year.
um, yes:
05-06:
222 assisted 3's
307 assisted 2pt Jump shots
209 assisted close shots (not dunks)
88 assisted dunks
04-05:
284 assisted 3's
169 assisted 2pt Jump shots
206 assisted close shots (not dunks)
202 assisted dunks
...
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bchaikin
Joined: 27 Jan 2005
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PostPosted: Thu Apr 01, 2010 8:48 pm Post subject: Reply with quote
A bye-product of this approach is that good passers on bad teams get adjusted upwards because of all the potential assists that were missed by their poor-shooting teammates.
fwiw you might want to rethink this line of approach - if you look at say players up and through the age of 30 (just to even out the field as many do not play past that age) over the last 15 years of the nba, a player for example like brevin knight threw for assists at a better ast/min rate than did players like jason kidd, steve nash, andre miller, and a host of others. his ast/min rate was bettered by only chris paul and deron williams...
yet the teams he played on averaged only about 30 wins a season. do you really think adjusting his assists upwards would make him in the minds of some the best "passer" in the game over the last decade and a half?...
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BobboFitos
Joined: 21 Feb 2009
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PostPosted: Thu Apr 01, 2010 11:35 pm Post subject: Reply with quote
bchaikin wrote:
A bye-product of this approach is that good passers on bad teams get adjusted upwards because of all the potential assists that were missed by their poor-shooting teammates.
fwiw you might want to rethink this line of approach - if you look at say players up and through the age of 30 (just to even out the field as many do not play past that age) over the last 15 years of the nba, a player for example like brevin knight threw for assists at a better ast/min rate than did players like jason kidd, steve nash, andre miller, and a host of others. his ast/min rate was bettered by only chris paul and deron williams...
yet the teams he played on averaged only about 30 wins a season. do you really think adjusting his assists upwards would make him in the minds of some the best "passer" in the game over the last decade and a half?...
why is it hard to believe brevin knight *could* be one of, if not the best, pure passers in the entire game? brevin was 5'10 (optimistically speaking) without a lot of athletic ability and 0 shooting ability. He had unbelievably quick hands, but even with a great STL%, wasn't ever considered a positive on defense. (And possibly was a detriment) But he had an 11 year career playing over 18,000 minutes. Clearly he was doing *something* well, right?
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bchaikin
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PostPosted: Fri Apr 02, 2010 1:16 am Post subject: Reply with quote
why is it hard to believe brevin knight *could* be one of, if not the best, pure passers in the entire game?... Clearly he was doing *something* well, right?
well then it depends on what your definition of what a "pure passer" is. if its a player that throws a ton of passes and gets alot of assists simply because he throws a ton of passes, then i'd say he could be...
the fact is that in today's game 56%-57% of all FGM have an associated assist. over the past 15 years that percentage goes up to close to 60%. if you assume say just 1/10 of all FGM are clearly on one-on-one plays where a basket is scored and there was no assist (and i'm guessing on that 1/10 number), then close to 2/3 of all of the other FGM had an associated assist - i.e. something like 2/3 of all other FGM preceded by a pass had that pass recorded as an assist...
so the question becomes what proportion of those assists on those other 2/3 of FGM were due more to the passing ability of the passer rather than the scoring ability of the player receiving the pass? or...
The issue essentially boils down to the chicken or the egg problem. Does the passer create the open shots for the offense or does the offense create open shots for the passer?
however if your definition of what a "pure passer" is is not simply just someone who gets alot of assists because he throws alot of passes, but someone who either (1) gets a higher percentage of assists per pass that he throws, or (2) increases the FG% of the players he throws passes to moreso that other passers do, then there should probably be a better measure than simply the number of assists thrown for by a player...
...because there are and have been many players who throw for alot of assists simply because they throw a ton of passes, as something like 2/3 of all FGM that were preceded by a pass had that pass recorded as an assist...
again for example looking at the past 15 seasons and all those players that have (a) played at least 3000 total minutes up to and through the age of 30, and (b) have thrown for assists at a rate of (again an arbitrary number here) say 9 ast/40min, you will find not only names like chris paul, deron williams, jason kidd, and steve nash, but also names like brevin knight, robert pack, sergio rodriguez, and jamaal tinsley...
are there people out there that consider players like pack, rodriguez, and tinsley to have been some of the best "passers" over the last decade and a half? or just as players who threw for a ton of assists because they handled the ball so much, shot infrequently, and threw a ton of passes?...
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DSMok1
Joined: 05 Aug 2009
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PostPosted: Fri Apr 02, 2010 7:59 am Post subject: Reply with quote
bchaikin wrote:
are there people out there that consider players like pack, rodriguez, and tinsley to have been some of the best "passers" over the last decade and a half? or just as players who threw for a ton of assists because they handled the ball so much, shot infrequently, and threw a ton of passes?...
Because I am looking at where the assist went to, I think the problem is resolved--there is almost no credit for an assist to a midrange jumper but there is a lot of credit for an assist to a layup. I don't care if they didn't shoot much--if their assists were going for dunks and layups, they should get some credit for it!
Interestingly, the players that get the biggest boost percentage-wise are the post players. Last year, Yao and KG both got a 30% boost because of where their assists went to. The ones hurt the most are players who just made passes to the midrange--Stuckey, Chalmers, Prince, Lee.
Oddly enough, despite the ones helped often being post players, Andrew Bynum is one hurt the most by the adjustment.
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habetw4
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PostPosted: Fri Apr 02, 2010 9:04 am Post subject: Reply with quote
Are we to assume that there aren't good passers who throw a ton of passes? Are the two mutually exclusive? Surely, there are players who specialize in ball distribution just like there are those who exclusively specialize in rebounding, guarding the opponent's superstar, or defending the rim.
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bchaikin
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PostPosted: Fri Apr 02, 2010 1:48 pm Post subject: Reply with quote
Because I am looking at where the assist went to, I think the problem is resolved--there is almost no credit for an assist to a midrange jumper but there is a lot of credit for an assist to a layup. I don't care if they didn't shoot much--if their assists were going for dunks and layups, they should get some credit for it!
who should get some credit for it? the passer or the player who made the cut to the basket or got into position close enough to the basket to get the dunk in the first place?...
sine 04-05 both amare stoudemire and zach randolph have both been 20/10 players (or close to it). stoudemire has shot 57% on 2s, randolph 47%. stoudemire has played with primarily one PG (nash), randolph with at least four (four different teams) if not more. are you of the opinion that if randolph had played all 5 seasons with phoenix, and stoudemire with the 4 teams zach had played with, that those two 2pt FG%s would be reversed? all because nash supposedly throws passes that lead to layups and dunks (with no "assist" credit to the player who got the layup or dunk)?...
because if you watch both players stoudemire cuts to the basket far more often than does randolph. shouldn't he get credit for getting himself open often for a player like nash to get him the pass in the first place?...
was there a better "passer" than john stockton? from 1987-88 to 1996-97, ten years, john stockton passed for about 1000 assists/yr. no one else in the league passed for even 700 ast/yr. the following players played for utah during this time, but also for other teams (karl malone, mark eaton, and thurl bailey played primarily for utah):
tyrone corbin
jeff malone
jeff hornacek
david benoit
mike brown
blue edwards
antoine carr
felton spencer
adam keefe
tom chambers
when these 10 players all played for utah (and stockton was there throwing for his 1000 ast/yr from 8788-9697) as a collective group they shot a 49.9% 2pt FG%. for all the other teams they played with (22 in all) during their careers as a collective group they shot a 48.4% 2pt FG%...
now i would assume that of that 48.4% 2pt FG% with other teams that with some of those PGs they shot a bit worse than 48.4% and with some a bit better, meaning that some of those PGs threw for assists to these players where they shot 49%-50%, similar to stockton...
does that mean those PGs were as good of "passers" as stockton was?...
Are we to assume that there aren't good passers who throw a ton of passes?
again - what if your definition of a "good passer"?...
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DSMok1
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PostPosted: Fri Apr 02, 2010 2:05 pm Post subject: Reply with quote
bchaikin wrote:
who should get some credit for it? the passer or the player who made the cut to the basket or got into position close enough to the basket to get the dunk in the first place?...
sine 04-05 both amare stoudemire and zach randolph have both been 20/10 players (or close to it). stoudemire has shot 57% on 2s, randolph 47%. stoudemire has played with primarily one PG (nash), randolph with at least four (four different teams) if not more. are you of the opinion that if randolph had played all 5 seasons with phoenix, and stoudemire with the 4 teams zach had played with, that those two 2pt FG%s would be reversed? all because nash supposedly throws passes that lead to layups and dunks (with no "assist" credit to the player who got the layup or dunk)?...
because if you watch both players stoudemire cuts to the basket far more often than does randolph. shouldn't he get credit for getting himself open often for a player like nash to get him the pass in the first place?...
was there a better "passer" than john stockton? from 1987-88 to 1996-97, ten years, john stockton passed for about 1000 assists/yr. no one else in the league passed for even 700 ast/yr. the following players played for utah during this time, but also for other teams (karl malone, mark eaton, and thurl bailey played primarily for utah):
tyrone corbin
jeff malone
jeff hornacek
david benoit
mike brown
blue edwards
antoine carr
felton spencer
adam keefe
tom chambers
when these 10 players all played for utah (and stockton was there throwing for his 1000 ast/yr from 8788-9697) as a collective group they shot a 49.9% 2pt FG%. for all the other teams they played with (22 in all) during their careers as a collective group they shot a 48.4% 2pt FG%...
now i would assume that of that 48.4% 2pt FG% with other teams that with some of those PGs they shot a bit worse than 48.4% and with some a bit better, meaning that some of those PGs threw for assists to these players where they shot 49%-50%, similar to stockton...
does that mean those PGs were as good of "passers" as stockton was?...
Are we to assume that there aren't good passers who throw a ton of passes?
again - what if your definition of a "good passer"?...
I have no idea about actual "point" credit. I'm simply trying to see which assist is worth more than the others.
Here is what I am doing.
1. Calculate the UNASSISTED team eFG%. This is critical. THIS is where there is a correction for teammates.
2. Calculate the eFG% for all potential assist passes by the player. (This differs depending on how good the team is from EACH LOCATION on ASSISTED eFG%)
3. Subtract unassisted team eFG% from player assisted eFG% and multiply the difference times total # of opportunities.
4. Total all of the NBA; normalize the value to the total number of assists handed out.
Sure, some of the credit for actually being able to make the pass goes to the recipient of the pass... but they already get credit for the score, anyway.
If a player is playing for a good midrange team (where the eFG% is high on assisted midrange jumpers) the player will get credit. If the assisted eFG% on midrange jumpers is lower than the team unassisted eFG%... there was basically no value added. (Why was the shot taken?)
All of this is predicated on all players improving their opponents shot in a given position on the court by the same amount, which is obviously shaky ground. Perhaps Kidd's pass to Dirk is better than JJ Barea's pass to Dirk in the same location. Perhaps CP3's lob to the rim is better than Darren Collison's. But until we can estimate this (which will be impossible until "missed assists" are kept track of in PbP), this is about the best we can do I think.
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Mike G
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PostPosted: Fri Apr 02, 2010 5:54 pm Post subject: Reply with quote
DSMok1 wrote:
... I think the problem is resolved--there is almost no credit for an assist to a midrange jumper but there is a lot of credit for an assist to a layup. ..
Isn't the 'problem' resolved already? When you pass to high-% areas, you get more assists.
If you have 4 seconds to get a shot, a 33% shot might be as good as you are gonna get. So you get an assist on 1/3 of those passes.
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DSMok1
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PostPosted: Mon Apr 05, 2010 7:58 am Post subject: Reply with quote
Mike G wrote:
DSMok1 wrote:
... I think the problem is resolved--there is almost no credit for an assist to a midrange jumper but there is a lot of credit for an assist to a layup. ..
Isn't the 'problem' resolved already? When you pass to high-% areas, you get more assists.
If you have 4 seconds to get a shot, a 33% shot might be as good as you are gonna get. So you get an assist on 1/3 of those passes.
The "truth" is between my "adjusted assists" and the actual assists. One measures successes, the other tries to quantify value added.
True, that may be the best possibility given the situation, but it is also likely to not the best possibility if the person doing the passing were a bit better player, like a Steve Nash. Wouldn't you consider a player with 5 assists on dunks a better passer than a player with 5 assists on midrange jumpers?
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Mike G
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PostPosted: Mon Apr 05, 2010 8:19 am Post subject: Reply with quote
DSMok1 wrote:
Mike G wrote:
When you pass to high-% areas, you get more assists.
.
Wouldn't you consider a player with 5 assists on dunks a better passer than a player with 5 assists on midrange jumpers?
Suppose these players are equal in every respect, except that in a span of 20 possessions:
- Player A gets 6 passes into the hands of someone at the rim, resulting in 5 successful shots (dunks).
- Player B gets the ball 12 times to jumpshooters, who convert 5 times.
We don't know what they did with/without the ball on their other possessions. It could be A is the 'risk taker' and B is the 'play it safe' guy.
Maybe the teams play different styles (fastbreak vs halfcourt).
One guy did not feed a teammate for a shot on 8 possessions, and the other guy did not on 14 occassions.
Assists are equal to attempts * effectiveness.
If Player A could get 12 passes to players in dunking range, and they convert 10, then he has twice as many Assists as player B has. Now he's a better passer.[/i]
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DSMok1
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PostPosted: Mon Apr 05, 2010 11:22 am Post subject: Reply with quote
Mike G wrote:
Suppose these players are equal in every respect, except that in a span of 20 possessions:
- Player A gets 6 passes into the hands of someone at the rim, resulting in 5 successful shots (dunks).
- Player B gets the ball 12 times to jumpshooters, who convert 5 times.
We don't know what they did with/without the ball on their other possessions. It could be A is the 'risk taker' and B is the 'play it safe' guy.
Maybe the teams play different styles (fastbreak vs halfcourt).
One guy did not feed a teammate for a shot on 8 possessions, and the other guy did not on 14 occassions.
Assists are equal to attempts * effectiveness.
If Player A could get 12 passes to players in dunking range, and they convert 10, then he has twice as many Assists as player B has. Now he's a better passer.[/i]
effectiveness. The baseline effectiveness is NOT 0. This is where assists go wrong. What is the value added by the sequence of pass-shot? One must compare to what the team would do without the passing, the baseline UNASSISTED fg% of the team.
The current valuation of assists is attempts*effectiveness. My valuation is attempts*(effectiveness-unassisted effectiveness), scaled so the total is the same as just plain assists. I think it's a valuable number to be able to look at.
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Mike G
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PostPosted: Wed Apr 07, 2010 11:31 am Post subject: Reply with quote
DSMok1 wrote:
...
The current valuation of assists is attempts*effectiveness. My valuation is attempts*(effectiveness-unassisted effectiveness)..
Quote:
One must compare to what the team would do without the passing, the baseline UNASSISTED fg% of the team.
So, where is a table of teams' Unassisted FG% ?
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PostPosted: Wed Apr 07, 2010 1:32 pm Post subject: Reply with quote
Mike G wrote:
So, where is a table of teams' Unassisted FG% ?
That's the rub. If the play-by-play recorded whether there was a potential assist on the play, then it would be easy to account for. As it is, I had to estimate it based on the FG%, AST%, and estimated (from The Value of a Good Pass) FG% added by assist for each portion of the floor.
The estimated unassisted eFG% for each team:
Team UAeFG%
PHO 49.1%
ORL 48.5%
CLE 48.1%
TOR 46.6%
BOS 46.5%
GSW 46.4%
SAS 46.2%
DEN 46.1%
NYK 45.7%
UTH 45.6%
ATL 45.3%
MEM 45.1%
NOR 45.0%
LAL 44.8%
DAL 44.7%
POR 44.6%
MIA 44.3%
SAC 44.2%
HOU 44.0%
OKC 43.7%
PHI 43.6%
IND 43.4%
LAC 43.4%
CHA 43.3%
MIL 43.2%
WAS 43.1%
MIN 42.5%
CHI 42.2%
DET 41.9%
NJN 40.2%
If a team gets all of their dunks off of assists, no dunks are assumed in calculating the UAeFG%. Phoenix is so high because they shoot a ridiculously high percentage from 3, and unusually few of their 3's are assisted (I'm guessing Nash is shooting a lot of those!). Orlando is so high because unusually few of their layups/dunks are assisted and they shoot very well from the midrange (and few of those are assisted).
Do you see what I was trying to do? Obviously, this is incomplete unless we know the true UAeFG% and how much each team's eFG% improves in each area with each assist. It's a start, though.
