The good role players around him made him more valuable that season. They made the other team less efficient on offense and that allowed Iverson's efficiency relative to the opposition to rise. In essence, what happened was the Philly role players changed the game into where Iverson's relatively inefficient shots were good shots rather than mediocre shots. This is another case where context matters.
Thanks. I suppose you'd disagree with the claim of some that player's don't make eachother better.
But you said Iverson's stats suggested that his adjusted +/- would have been better in 2001 (if I didn't misread what you meant). I'm wondering what you meant by that statement. Is it his stats relative to what the opposing team did?
Yes, thanks. I guess you would put it closer to where Orating,Drating, Win Shares does? In between that and PER?
Unless I'm mistaken, Dean's Offensive Rating also assumes no value to shot creation. (Which is not to say that Dean sees no value in shot creation, it's just not done in that particular metric.)
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Wed Aug 02, 2006 11:56 am Post subject:
deepak_e wrote:
Thanks. I suppose you'd disagree with the claim of some that player's don't make eachother better.
But you said Iverson's stats suggested that his adjusted +/- would have been better in 2001 (if I didn't misread what you meant). I'm wondering what you meant by that statement. Is it his stats relative to what the opposing team did?
The evidence seems to suggest that players who shoot a lot, on average, increase the offensive efficiency of their teammates. But whether I agree or disagree with that statement depends on how someone defines "better." Adding a player who shoots a lot will likely reduce his teammates' scoring.
I probably should have said that the combination of Iverson's stats and his teams' stats suggested that his adjusted plus/minus would have been better in 2000-01.
Joined: 13 Jan 2005 Posts: 168 Location: Iowa City
Posted: Wed Aug 02, 2006 11:59 am Post subject:
admin wrote:
Ben wrote:
Yes, thanks. I guess you would put it closer to where Orating,Drating, Win Shares does? In between that and PER?
Unless I'm mistaken, Dean's Offensive Rating also assumes no value to shot creation. (Which is not to say that Dean sees no value in shot creation, it's just not done in that particular metric.)
That's what I thought too, but then they did pretty well in the correlations with plus-minus. Is that because they incorporate team defense?
Instead of Iverson I looked at Tim Duncan and Spur players with and without him and someone else in. Without some see a small turnover rate increase (+0.1 to 0.3 per 40 minutes) increase but others dont and the FG% changes seem fairly small too (0-3% on FG%) though these things add up and small can still be significant. The type and quality fo role player matters. Some are more self-sufficient, able to create on their own, shoot efficently and more often without the star and San Antonio seems to have put those type players around Duncan and on the court when he is not on. The offensive ratings of the main players with and without Duncan seem to be within 1 point. Duncan's full on/off is only 2.6 pts on team offense. Duncan and Iverson are different positions, different star types, maybe the polar opposites in some ways. It is not just them (and not all one way), it is the nature of the role players too- fit with and fit without the star are both important and maybe this last part was better executed in San Antonio, though Philly doesnt play without Iverson as much (less than half as much in regular season, playoffs probably would be a good deal closer). Team FG% on/off with Iverson +3.4%, Duncan -0.3%. Iverson shooting rate is about 30% higher and Dan's information suggests that would be missed more. Perhaps the quality of replacement varies in these cases too (Ollie and Salmons lower weighted average offensive PER than Horry). Complicated story to sort out.
Last edited by Mark on Wed Aug 02, 2006 2:59 pm; edited 4 times in total
Yes, thanks. I guess you would put it closer to where Orating,Drating, Win Shares does? In between that and PER?
Unless I'm mistaken, Dean's Offensive Rating also assumes no value to shot creation.
Not explicitly, no. He suggests adding one point to the ORtg for every 1% increase in possession percentage. Presumably 20% is the base percentage; therefore, a player with a 114 ORtg using 24% of his team's possessions would have a "true" ORtg of 118.
Yes, thanks. I guess you would put it closer to where Orating,Drating, Win Shares does? In between that and PER?
Unless I'm mistaken, Dean's Offensive Rating also assumes no value to shot creation.
Not explicitly, no. He suggests adding one point to the ORtg for every 1% increase in possession percentage. Presumably 20% is the base percentage; therefore, a player with a 114 ORtg using 24% of his team's possessions would have a "true" ORtg of 118.
Does he also say to subtract points from ORtg for players below 20%?
Dan, thinking about Iverson vs Duncan I wondered was your work on impact of high shooting rate guys paced adjusted? If it is, then a lot of this may not be on point.
But could a lot of Iverson's impact by as a major pace changer (while Duncan is not) instead of making things easier for teammates in halfcourt, with running presumably leading to higher FG%? I see Philly last season 6th fastest pace overall but in 2001 it was 19th. Was the pace change a mistake? Has it been better for Iverson than the team as a whole? It isnt the only factor as their success rate changed before the pace did but the faster pace the last two seasons doesnt seem the answer, so far with these players and coach. Anyone know Philly's pace and offensive efficiency without Iverson over the recent period, any big difference from glory years to now for these?They could be computed from b-r.com data (perhaps later). I see the basic Iverson on/off team scoring differential in 2005-6 is twice what it was in 2002-3 from 82games.
Last edited by Mark on Wed Aug 02, 2006 3:31 pm; edited 4 times in total
Yes, thanks. I guess you would put it closer to where Orating,Drating, Win Shares does? In between that and PER?
Unless I'm mistaken, Dean's Offensive Rating also assumes no value to shot creation.
Not explicitly, no. He suggests adding one point to the ORtg for every 1% increase in possession percentage. Presumably 20% is the base percentage; therefore, a player with a 114 ORtg using 24% of his team's possessions would have a "true" ORtg of 118.
Does he also say to subtract points from ORtg for players below 20%?
Well, yes, but I thought that would be understood.
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Wed Aug 02, 2006 4:33 pm Post subject:
Offensive minus defensive rating does better if that possession rate adjustment is added. It is right up their with Win Shares.
Another thing. I can build a prediction model using only minutes played and team wins and come up with individual ratings that predict adjusted plus/minus ratings as well as PER and Wins Produced. And I don't even need to position adjust.
And if I aggregate this up to the team level, I would predict team wins almost perfectly.
Another thing. I can build a prediction model using only minutes played and team wins and come up with individual ratings that predict adjusted plus/minus ratings as well as PER and Wins Produced. And I don't even need to position adjust.
( I leave some others out, including roland rating or just counterpart points or PER and protrade in these cases for lack of scores)
Also is there anything notable about the comparative ability of the methods you've scored to accurately grade the top 4 teams in the league by regular season record or appearance in conference finals? Average correlation is a main thing but accuracy with strongest teams is also a valuable feature.
Last edited by Mark on Fri Aug 04, 2006 11:11 pm; edited 4 times in total
Another thing. I can build a prediction model using only minutes played and team wins and come up with individual ratings that predict adjusted plus/minus ratings as well as PER and Wins Produced. And I don't even need to position adjust.
And if I aggregate this up to the team level, I would predict team wins almost perfectly.
So is this a way of saying that PER and WP are really poor predictors of your adjusted plus/minus ratings, or that minutes played and team wins are extremely vital in accurately rating players?
Your statement makes sense - team quality and minutes played would tend to lead to some accuracy in +/-. But I guess I don't understand the usefulness of this.
Also, as a general comment on this entire thread... All we (and by we, I mean Dan) seem to be doing is talking about which of these other rating measures we use or have been introduced to (WP, WS, PER, OEff-DEff, etc.) help predict Dan's ratings. We probably established as a group a year ago that Dan's ratings were pretty darn good, with a very solid methodology and sensible results. But I guess I'm missing the value of judging these correlations instead of judging the success and merits of the ratings systems on their own?
In other words, how do we know Dan's ratings are the best? If we don't know that, why are we judging other systems by how closely they predict Dan's? How else can we judge the systems without buying a basketball team?
On the whole, I agree that Wins Produced is lacking, mostly because it undervalues production in favor of overvaluing efficiency. But I'm not particularly convinced any measure we've seen is close to vastly superior to the others. Because basketball is so nuanced (especially in comparison with baseball), it might take seeing the implementation of certain rating systems in a predictive sense to get tons further on parsing the quality of those systems. (Whereas in baseball, the theory pretty definitively explains why OPS and VORP are important.) I think I fit in with the +/- side of the equation moreso than any others, and I wanted to stand up and clap when Dan started talking about using correlations to judge which stats tell us about other player qualities (that is really important), but there's a lot of noise everywhere. _________________ SactownRoyalty.com tziller@gmail.com
Another thing. I can build a prediction model using only minutes played and team wins and come up with individual ratings that predict adjusted plus/minus ratings as well as PER and Wins Produced. And I don't even need to position adjust.
That would be very interesting. How would you do that exactly?
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Wed Aug 02, 2006 9:55 pm Post subject:
Ziller, that was a very good post. I don't think any of this relies upon adjusted plus/minus ratings being the gold standard for rating players in all situations. In particular, I have repeatedly noted that adjusted plus/minus ratings are not always the best thing to use for rookies or players who have not played a lot of minutes. Also, for partial season analysis, adjusted plus/minus ratings are probably not that useful.
But I think it is easier to argue that if we could observe a player for tens of thousands of minutes in lots of different contexts, adjusted plus/minus ratings would tend to get things right; they would be "unbiased."
That is all that I am relying upon in this analysis, since by looking at the correlations of nearly 1200 player-seasons, that is in essence what I am doing. So I think this is a valid way to analyze various metrics - although the fact that my statistical rating comes out the best is probably not good evidence that it is better than the others. Unlike the other measures, it is designed to predict adjusted plus/minus ratings so it almost has to do better.
The rating based upon wins and minutes was nothing that I was advocating; it was more a way of putting this conversation in perspective.
And finally I apologize to those posts I have not answered, including Mark's request for a meta-rating.
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