PER is a pretty bizarre statistic. I really don't understand it. Rodman had a 17 PER in 91-92, which according to Bchaikin was his best season overall. As a Knicks fan, I happen to know that Eddy Curry also posted a 17 this year, while finishing second in the league in turnovers.
How does that work? Rodman averaged 22 rebounds per 48 that year and committed only 2 turnovers for a +20 in gaining and maintaining possession.. Curry was at +4.6. So the 15 points Curry outscored him by is less than the difference between them in their impact on possession.
How could they possibly have the same PER? I just don't get it.
How does that work? Rodman averaged 22 rebounds per 48 that year and committed only 2 turnovers for a +20 in gaining and maintaining possession.. Curry was at +4.6. So the 15 points Curry outscored him by is less than the difference between them in their impact on possession.
1. You suggest that Rodman was gaining +20 possessions per 48. At face value, this is as good as you claim. The reason PER doesn't rate Rodman off the charts, however, is that it doesn't consider securing a Defensive Rebound as equivalent to gaining a possession -- like you suggested. Yes, it is typically the final act in gaining the possession, but before it can happen a lot of defense is played. The entire team contributes in an effort to deny easy shots and ultimately put up a low percentage shot that will miss. And even after that everyone attempts to box out their man so that someone on the defensive team can get the rebound.
By crediting Rodman (or any player) with the full value of a possession for securing a defensive rebound you are basically rating him as single-handedly stopping an entire team. If Rodman really was one man defensive force on 16 or so plays per 48 minutes, then he would deserve the kind of credit you want to give him. I think that it is obvious that he only played a part.
2. The other difference in assumptions that PER makes is that Usage Rating matters. You point out that he only turned the ball over 2 times per 48 minutes. But that's only because his teammates didn't dare ever throw him the ball. In many of his great rebounding years his turnover rate was over 20%. His Usage Rate was down around 10% -- half of his share. When he put up a rare shot his efficiency was often terrible. Basically, any team with Rodman on the court had to play 4 on 5 on offense. PER thinks that matters, and it penalizes him for it.
My understanding is that WoW thinks otherwise. Grabbing a defensive rebound is the same as single-handedly stopping the opposing team on offense. And it doesn't matter if you are almost completely useless on offense, as long as you stay out of the way. By that criteria, then yes, Rodman would be one of the best.
The 6 point star & team ranking exercise I posted earlier in thread is just a rough guide on contender status. A higher number doesnt ensure victory of course. But all champs in last 10 years were at least a 5 and all finalists except the Indiana Pacers were at least a 4. The main advantage of this system it is shows stars alone don't determine but also team strength without enough star power backbone might not be enough in the playoffs on its own either. It takes an adequate combination. There may be more wiggle room about what is enough than in this presentation but the wiggle room probably isnt that large. The Pacers did better than their score because they had 4 Factor hammers, 1 major (own FG%) and at least 1 minor (FG% allowed) as described in team factor wins thread. The third team criteria of point differential does a good job of indicating when an offensive or defensive efficiency weakness is being adequate offset by the other strength.
Joined: 27 Jan 2005 Posts: 522 Location: cleveland, ohio
Posted: Mon Sep 10, 2007 8:55 pm Post subject:
A much shorter way of saying it would have been that a 4% difference in TS% is a big difference in shooting efficiency.
for a simple calculation, magic shot 50.9% in 88-89 or 579 FGM on 1137 FGAs. 4% less would have been 46.9% or 533 FGM. that's 579 - 533 = 46 FGM over 77 games, or (46 x 2)/77 = 1.2 more pts/g (not counting 3pters). from a team perspective with 46 more misses that'd be about 1/3 of those misses rebounded by the offense with some subsequent scores. so that 1.2 pts/g would be in reality closer to about 1 pt/g (perhaps slightly more or less). that makes up partly for 2.1 zero point team possessions per game since a team possession is on average worth close to about 1.0 point...
And 5 more assists per 48 is a big difference.
i don't see it - in terms of wins generated or how a player's stats contribute towards his team's wins. there are many players who have rung up high numbers of assists (or ast/48min) but have contributed little to their team's fortunes (kevin porter, brevin knight), and team rates of ast/fgm do not correlate well with wins...
Rodman had a 17 PER in 91-92, which according to Bchaikin was his best season overall.
possibly his best season overall, i'd have to simulate all (or most) of his seasons to be sure...
I look at this comp (Curry/Rodman), and it makes my head spin.
fwiw when i simulate the 06-07 knicks with curry for 40 min/g and 82 games, then replace curry with rodman 91-92, the team wins on average 10-11 more games per average 82 game season with rodman...
reverse this and simulate rodman on the 91-92 pistons for 40 min/g and 82 games, then replace him with curry 06-07, the pistons win 14-15 more games with rodman per average 82 game season...
those are some huge differences...
in 06-07 curry got few rebounds, few steals, few blocks, and a ton of turnovers. as a matter of fact, the only starting C last season with less (REB+ST+BS)/40min than curry (9.1/40min) was the nets' jason collins (8.5/40min). the league average for a C (with >= 20 games started) was 13.4/40min...
also curry shot quite well in 06-07 at 57.6% (585/1016), but had 295 TOs. from a team perspective a TO is basically the same as a missed FGA rebounded by the defense (a zero point team possession). since knicks' opponents got 69% defensive rebounds, that'd be like curry committing say just 125 turnovers (like mehmet okur in 06-07) but missing an additional (295-125)/0.69 = 246 FGAs, i.e. scoring 19.5 pts/g but shooting just 585/(1016+246) = 46.4% (league average C shot 51%) with few rebs, st, and bs. who'd want that?....
By crediting Rodman (or any player) with the full value of a possession for securing a defensive rebound you are basically rating him as single-handedly stopping an entire team.
correct, however....
If Rodman really was one man defensive force on 16 or so plays per 48 minutes, then he would deserve the kind of credit you want to give him. I think that it is obvious that he only played a part.
he was all-D 1st team 7 times in 8 seasons, and DPOY in 89-90 and 90-91, and not because of his rebounding. he was quite possibly the best defensive player over a stretch of a decade (late 1980s to late 1990s) who wasn't a premier shot blocker. when playing for the spurs/bulls in the mid-1990s he often guarded shaq rather than david robinson or a bulls C...
The other difference in assumptions that PER makes is that Usage Rating matters. You point out that he (rodman) only turned the ball over 2 times per 48 minutes. But that's only because his teammates didn't dare ever throw him the ball. In many of his great rebounding years his turnover rate was over 20%.
in curry's and rodman's first 6 seasons in the league (curry has played just six years), curry's rate of turnovers per touch were much higher than rodman's. curry turned the ball over with 12% of his touches (1 turnover for every 8-9 touches on offense) and rodman turned the ball over with 9% of his touches (1 turnover for every 11 touches on offense). there is very little a player can do on offense to help his team (i.e. generate wins) when he turns the ball over on a very high rate of 1 out of every 8-9 touches (1 out of every 7-8 touches curry's last 2 seasons), unless he limits his touches or contributes on offense in a major way without the ball, such as with excellent offensive rebounding (or by getting to the line a ton and hitting his FTs), but curry has been a poor offensive rebounder (and while he gets to the line a ton has a career FT% of less than 65%)...
he was all-D 1st team 7 times in 8 seasons, and DPOY in 89-90 and 90-91, and not because of his rebounding. he was quite possibly the best defensive player over a stretch of a decade (late 1980s to late 1990s) who wasn't a premier shot blocker. when playing for the spurs/bulls in the mid-1990s he often guarded shaq rather than david robinson or a bulls C...
No argument there. PER does not measure defensive (or any other) contributions that don't show up in the box score, and it has never claimed to do so. PER is a summary of box score accomplishments, and it is on that level that it ranks Rodman to be an average player. Rodman was almost certainly a much more valuable player because of his defensive abilities, but that is beyond the scope of what PER sets out to measure.
Joined: 31 Dec 2004 Posts: 912 Location: Durham, NC
Posted: Mon Sep 10, 2007 9:19 pm Post subject:
Flint wrote:
How does that work? Rodman averaged 22 rebounds per 48 that year and committed only 2 turnovers for a +20 in gaining and maintaining possession.. Curry was at +4.6. So the 15 points Curry outscored him by is less than the difference between them in their impact on possession.
How could they possibly have the same PER? I just don't get it.
Curry also scored more efficiently (at a higher TS%), and did so in 5 less MPG. Remember that PER is a per-minute stat, so stretch out Curry's production by 40/35 MPG difference.
Bchaikin - Are you including ft's in your analysis of Magic? The 4% difference in TS% reflects the difference there. The 88-89 version shot 91% from the line. Young Magic was at 76%. If you included ft's rather than just fg's, does that make an impact?
Re assists, I don't diagree that assists are less important than turnovers, rebounds, attempts, and points. But it is an advantage for Old Magic.
Your simulations are interesting, and absolutely in line with how I would view Rodman's value relative to Curry's. I just find it amazing, ridiculous really, that PER rates Curry's contributions last year as being equal to Rodman at his absolute prime. Rodman averaged just two less offensive rebounds per 48 than Curry did overall. Curry last year was one of only two centers in the three point era to average less than ten rebounds per 48 and five turnovers. (Darryl Dawkins is the other.) And his assist numbers were horrible. He was basically without historic precedent, which is why the Curry Line feature over at Yahoo, a basketball version of the Mendoza line, was so apt. And yet, because he scores well his PER was well above average. This doesn't make sense.
Btw- do you have a link to a post in which you have described the simulation process?
ASimpkins - re the WOW crediting players with team defensive accomplishments, I just don't really buy it. I know it is the big bone of contention, but I don't care to argue the point. I can only say that I saw Eddy Curry allow so many second chance opportunities last year, it killed me. There was one game against Detroit, a three overtime game we actually won, where Curry allowed Mohammed three offensive boards that led to thre crucial second chance buckets. Especially for a center, I think those d-boards matter a lot.
And re Rodman, the basic point to me here is that Rodman's stats were much better in every way than Curry other than a small difference in scoring efficiency, (that year anyway), and a big difference in points scored. How much difference can those extra points Curry scores really make?
Having Rodman out there does force his teammates to take more shots, but thats what most ballers do, they take shots. Yes, they did so less efficiently than Curry did last year, for sure. But Rodman was hardly useless on offense. He generated 4.3 more shots per 48 than Curry did on the offensive end. In my mind, there is no way a 60% ts% can make up that difference.
Rodman's team will take the 22.6 odd shots and free throws Curry took at a lower efficiency, granted. But say that we assume something ridiculous, that even with Rodman's contribution of 10 points on 10.2 net shots (adding up fga and .5fta) at 57.4%, those 22.6 shots only go in at a 50% ts% rate. that means his team scores 22.6 points, four less than Curry. However Rodman's team takes 4.3 more shots. So their net point total, if you carry through the 50% ts%, is 26.9, or .3 more than Curry.
And we haven't even assessed the damage Curry does to the Knicks with his turnovers. Rodman commits two. And in the course of taking the extra 12.x shots he doesn't take that Curry does, his teammates commit turnovers. But I really doubt they commit three more turnovers taking those extra shots. Overall, there are a lot less turnovers being committed by Rodman's team.
Many people seem to think Rodman was an offensive liability. I think the numbers show Rodman had to be a much much more valuable player to have on the court on the offensive end than Curry. Offensive rebounds are more important than scoring from the center position in my mind than shooting. Even a very efficient and prolific scoring center is going to have a hard time keeping up with a center who shoots almost as well as he does on lower volume, but outrebounds him offensively by a good margin. The extra shots his teams take are just a huge source of value.
I think its ridiculous that Rodman isn't going to the Hall of Fame. Somehow people lump him in with Horry I think, as a role player who hooked up with great teammates. I think Berri's view is much more accurate. Rodman was the best player on the Piston Championship teams, and as important to the Bulls teams when he was on the court as any player other than Jordan.
i don't know that Pippen was better than Rodman. Considering how well he rebounded that year, and especially his 8.2 orpg, I would say no. But he clearly took a lot of rebounds from his teammates defensively. I don't know, see p. 144 of the WOW and let me know what you think. Personally, I preferred Rodman as a player, but I may be alone in my love of rebounders. I think my own playing style (in high school) makes me view the game a bit differently than most.
i don't know that Pippen was better than Rodman. Considering how well he rebounded that year, and especially his 8.2 orpg, I would say no. But he clearly took a lot of rebounds from his teammates defensively. I don't know, see p. 144 of the WOW and let me know what you think. Personally, I preferred Rodman as a player, but I may be alone in my love of rebounders. I think my own playing style (in high school) makes me view the game a bit differently than most.
I guess I just don't get how you look at things. You just made a point of talking about the huge disparity between Rodman & Curry - since Rodman was better (or MUCH better in case of rebounding) statistically at everything other than TS%, usage, & scoring.
Well - Pippen was better than Rodman at everything statistically other than rebounding (obviously) - MUCH better in scoring, assists, usage, steals, blocks, A/TO, TS%, win shares (including PW%), & PER.
It sounds like to me the ONLY thing that seems to matter to you is if the guy is a great rebounder & possibly a good defender. He can be pretty much a complete non entity offensively (outside of offensive rebounds) - and you don't seem to think that affects his team negatively whatsoever.
Whether you want to believe it or not - usage matters.
As for giving credit to role players (Rodman is the most extreme epitome of that - his role was solely rebounding & defense) as being the backbone to a good team- that is all fine & dandy. However, to seemingly ignore the role of higher usage players (especially an ALL AROUND great player like Pippen) as being vital in a lineup so that a good role player or two can see court time despite their limitations in certain areas (usually offensively) seems short sighted.
I wonder what the final score would be between a team full of Scottie Pippens and a team full of Dennis Rodmans? Those Bulls teams couldn't win a championship without Pippen imo. They still would have won championships (although maybe not at impressively) without Rodman.
Dennis Rodman NEEDS players like Jordan, Pippen, David Robinson, Thomas, Dumars, etc. in order for his team to succeed because of his own obvious limitations. He can then help make them & his team greater. Those players don't NEED a player like Rodman in the lineup to succeed - although it doesn't hurt. _________________ www.goodstats.net
Joined: 14 Jan 2005 Posts: 1649 Location: Delphi, Indiana
Posted: Tue Sep 11, 2007 7:59 am Post subject:
I am pretty sure Berri ranked Rodamn as the best player in the NBA thru 1999 or 2000, by which time he was truly a bit player. He had outlived his usefulness, there was no niche role in which he was considered valuable, and yet Berri thought he was the best player around.
Flint drifted from a reasonable argument that peak (1992) Rodman was more valuable than 2007 Curry, to 2nd-best player on the greatest team ever (Bulls), to best player on the champion (1989-90) Pistons.
Rodman won't get to the HOF anytime soon. Working against him are emotional/social problems that sabotaged some of his teams (SA '95, notably). Bulls managed to corral him for the most part, but still there was the photographer-kicking incident and others.
Statistically, he was near the lowest-of-the-low in some stats (scoring, FT%), and highest-ever in others (rebounding). One in ten rating systems may rank his career highly enough; but it's doubtful that will sway the Hall. _________________ 40% of all statistics are wrong.
ASimpkins - re the WOW crediting players with team defensive accomplishments, I just don't really buy it. I know it is the big bone of contention, but I don't care to argue the point.
I don't really want to argue the point either. I'm not really trying to change your mind on who's-better-than-who as much as I was trying to explain why PER works the way it does. Your previous post expressed a lot of bewilderment on the matter (though perhaps it was just rhetorical). You may not ultimately agree with the assumptions that PER makes, but they are coherent and understandable:
Credit defensive rebounds at about 1/3 of a possession instead of the entire possession, and penalize players for hiding on the offensive end. That's how a fantastic one-dimensional rebounder like Rodman ends up ranked about the same as a good one-dimensional scorer like Curry.
Joined: 03 Jan 2005 Posts: 685 Location: Washington, DC
Posted: Tue Sep 11, 2007 11:36 am Post subject:
When I read Berri's book, I thought I was starting to see some merit to his approach. And there may be some merit -- it's a good book. But...then I look a little closer and, I dunno.
Out of curiosity, I ran a search at b-r.com for the top rebound rates since 1977-78. Players needed at least 15,000 minutes to qualify. Then I ran Berri's simplified Win Score metric on those players -- pts + reb + stl + .5 x ast + .5 x blk - fga - tov - .5 x fta - .5 x pf. Then I divided by minutes to get a per minute Win Score.
According to this metric, Rodman rates as the 2nd best player among the top rebounders behind only Charles Barkley. He ranks ahead of players like David Robinson, Shaq, Moses Malone, Hakeem, Larry Bird, KG, Tim Duncan, Kareem, Karl Malone, Dirk, and Elton Brand.
I dunno, but to me there's something not right with a sytem that rates Rodman as "better" than players like Bird, Duncan, Shaq, and Kareem. _________________ My blog
When I read Berri's book, I thought I was starting to see some merit to his approach. And there may be some merit -- it's a good book. But...then I look a little closer and, I dunno.
Out of curiosity, I ran a search at b-r.com for the top rebound rates since 1977-78. Players needed at least 15,000 minutes to qualify. Then I ran Berri's simplified Win Score metric on those players -- pts + reb + stl + .5 x ast + .5 x blk - fga - tov - .5 x fta - .5 x pf. Then I divided by minutes to get a per minute Win Score.
According to this metric, Rodman rates as the 2nd best player among the top rebounders behind only Charles Barkley. He ranks ahead of players like David Robinson, Shaq, Moses Malone, Hakeem, Larry Bird, KG, Tim Duncan, Kareem, Karl Malone, Dirk, and Elton Brand.
I dunno, but to me there's something not right with a sytem that rates Rodman as "better" than players like Bird, Duncan, Shaq, and Kareem.
Any player that gets alot of rebounds, and doesn't do much of anything offensively (doesn't take, therefore miss, many shots and doesn't touch the ball enough to garner many turnovers) will rate very well in Berri's system.
As far as I can tell - Berri's system is flawed most in terms of overvaluing low usage/big rebound players, much the same way it can be argued that PER is flawed by overvaluing huge usage/low efficiency players.
Neither system (obviously by the nature of linear weights) sees any value of defensive stopper/no offense no rebounding (aka Bruce Bowen) type player.
If Dan R. ever fully hashed out and updated his system (he may have, I dunno) - that would almost certainly be the best player "ranking" system I know of. _________________ www.goodstats.net
Joined: 27 Jan 2005 Posts: 522 Location: cleveland, ohio
Posted: Tue Sep 11, 2007 1:28 pm Post subject:
...to me there's something not right with a sytem that rates Rodman as "better" than players like Bird, Duncan, Shaq, and Kareem.
agreed - but i can see rodman rated almost as good as some of the very best PFs. on a very poor offensive team, like for example the 02-03 denver nuggets, simulation shows - on a 40 min/g and 82 game basis - dennis rodman 91-92 generating 8-9 more wins than juwan howard 02-03. but it also shows PFs like karl malone 89-90, elton brand 05-06, tim duncan 04-05, larry bird 87-88 (ok SF not PF), and shawn marion 05-06 generating 14-15 more wins per average 82 game season replacing howard. so rodman here generates 6-7 less wins, quite a large differense....
but on a good offense, very poor defensive team (like the 05-06 seattle sonics, and whose PFs were not a key reason for the team's good offense), or on a team replacing a starting PF who was both a poor defender and a poor rebounder, like the 95-96 cleveland cavaliers (danny ferry, but who shot well and committed few turnovers), on a 40 min/g and 82 game basis simulation shows rodman generating close to as many wins (within 1-2 wins) as the above mentioned star PFs....
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