APBRmetrics

[Harold Almonte]

It was what Statman suggested some post ago. How did you do? Comparing counterpart's PER against the average PER of the position? Can this +/-PER compares oranges (perimeter) with apples (insiders)? Some split among starters, second unit, and deeper bench position PER?

Or you just positioned DRTG?

[Harold Almonte]

DanR weighted his defensive composite http://www.82games.com/rosenbaum3.htm 60% to +/-,on/off, and 40% +/-stats. He said he used to give more weight to stats before.
RRating weights his overall composite something near to 70% to counterpart and 30% to on/off. He used 50-50 before.

[JNichols42887]

[JNichols42887]

I just calculated DCS scores for the 2006 season and they (thankfully) are pretty similar to 2007. For example, with Memphis in 2006, Battier had a DCS of 44.74. With Houston in 2007, his score was 44.64. Obviously that was one of the closer ones, and there were some players with pretty big jumps or declines (usually those players changed teams and did not get a ton of minutes).

[kjb]

I'd be interested in seeing the 2006 results, but even moreso, the 2005 (if you're up to it). That's because I tracked the Wizards pretty extensively in 2005 and I'm interested to see how DCS compares.
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[JNichols42887]

[Carlos]

Very interesting. All Memphis players's ratings took a dive in 06-07, of course. Gasol went from 27.76 in 06 to -12.2 in 07, for example. It seems to me that there is a strong "system effect" at play. That is, being a member of a very good (or very bad) defensive team makes you look better (or worse) than you really are. I mean, Memphis's defense went from good in 06 to terrible in 07 and obviously SOMEBODY defended worse in 07, but the sudden change in a player from "very good defender" to "below average" suggests that there is something more here than just variation in individual ability.

[bchaikin]

It seems to me that there is a strong "system effect" at play.

memphis went from the 2nd best/lowest points allowed per defensive team possession in 05-06 to the highest/worst in 06-07 among the 30 teams in the league. however in dropping from 49 wins in 05-06 to just 22 wins in 06-07, their points scored per offensive team position actually got better...

3 of the 5 players to play the most minutes for the grizzlies in 05-06 were shane battier, an excellent defender, and eddie jones and bobby jackson, two very good defenders. none of the three played for the team in 06-07. when you lose not one or two but three of your best defenders among your top five minutes played players, your defense will most likely get worse, regardless of the coach or system...

[JNichols42887]

I agree. Right now I think there are two flaws with the system: It is highly influenced by what team you're on (as evidenced by Ginobili looking so good every year), and it doesn't account for matchups. I may be able to fix the first problem though. I'm just not sure if I want to punish bad players on good teams and vice versa. For example, some of Gasol's decline surely was a result of the Grizzlies losing some good defenders and becoming terrible defensively. But I also think that individually he probably played worse too. If everyone around you is bad on defense and doesn't care, you're probably not going to put forth your best effort either.

[Carlos]

Or maybe playing in a very good defensive team in 06 made him look better than he really was.. The thing is, I'm not sure how to (or if it's really possible to) separate individual defensive ability from team system and teammates's ability. Playing with good defenders in a good system means your guy receives worse entry passes, you don't have to help as much, defensive help arrives faster, there are fewer targets for the opponent to pass to, etc. These things don't really show in counterpart production and I'm unsure of how to account for them.

[KeeneKaufmanWheeler]

I've found this research to be very interesting, and I've tinkered with the data a little to try and make the data easier to compare across teams.

I used my own ranking system which I like to extrapolate across whole teams (to create a "team offense ranking") and opponents (to give a "Team Defense" ranking). This gives me a relative measure to compare how much better one team is than another.

I then applied these percentages to DCS to come up with a Team DCS. This gave me a starting point to try and factor in team performance into individual ranking.

First, I decided to use the original -- version one -- DCS rankings. I felt that there were several players that jumped out at me as being way off in version two (notably Earl Boykins being considered an average defender).

I then filtered the data twice: once to factor out team-to-team differences and another to factor the individual’s influence on team performance.

For the team weighting, I added/subtracted half of the percentage difference that each team deviated from the norm (half of the difference because I theorized that since defense is part ability and part coaching style, I wanted one filter to be coaching related and one player ability related). For the individual weighting I calculated the percentage of minutes each player had played and factored in the value of the player vs. that of an average replacement-level player (a 50 DCS player).

I feel that the results look pretty accurate. They are definitely best when comparing players to their contemporaries at the same position – it seems like point guards in particular get knocked down significantly. Maybe they tend to have more offensive responsibilities and tougher nightly defensive matchups than other players?

The results (top 5 at each position):


OVERALL RANK ADJUSTED DCS
2 104.241 okafor,emeka cha C
3 104.058 duncan,tim sa C
4 102.805 biedrins,andris gs C
5 102.676 o'neal,jermaine ind C
24 96.242 nesterovic,rasho tor C
1 105.754 garnett,kevin min PF
6 101.591 marion,shawn pho PF
11 99.824 varejao,anderson cle PF
12 99.798 thomas,tyrus chi PF
13 99.631 millsap,paul uta PF
7 101.490 balkman,renaldo ny SF
15 98.921 battier,shane hou SF
18 98.171 james,lebron cle SF
23 96.592 ariza,trevor orl SF
25 95.292 artest,ron sac SF
9 101.263 ginobili,manu sa SG
29 94.598 wells,bonzi hou SG
37 91.200 sefolosha,thabo chi SG
41 90.734 wade,dwyane mia SG
43 90.026 mcgrady,tracy hou SG
8 101.339 davis,baron gs PG
10 100.938 rondo,rajon bos PG
22 96.740 alston,rafer hou PG
33 92.901 harris,devin dal PG
46 88.764 ewing,daniel lac PG

And the bottom at each position:

236 26.334 voskuhl,jake cha C
274 13.188 blount,mark min C
297 6.771 brezec,primoz cha C
320 -0.850 okur,mehmet uta C
326 -5.105 curry,eddy ny C
288 9.470 randolph,zach por PF
293 7.330 diaw,boris pho PF
294 7.286 robinson,cliffor nj PF
315 -0.071 warrick,hakim mem PF
319 -0.670 gomes,ryan bos PF
298 6.496 kapono,jason mia SF
309 1.480 williams,shawne ind SF
317 -0.393 hayes,jarvis was SF
318 -0.585 szczerbiak,wally bos SF
323 -3.116 morrison,adam cha SF
307 3.268 jones,dahntay mem SG
310 1.257 carroll,matt cha SG
312 0.692 green,willie phi SG
313 0.376 hassell,trenton min SG
316 -0.183 crawford,jamal ny SG
321 -0.966 atkins,chucky mem PG
322 -1.232 mcinnis,jeff cha PG
324 -3.749 lue,tyronn atl PG
325 -4.944 williams,deron uta PG
327 -5.987 marbury,stephon ny PG

The full data is posted at http://briefcase.yahoo.com/ipmhoops

Oh, and one difficulty with even attempting this analysis: the fact that charges taken is not a stat.

I think the results do a pretty good job of sorting the players relative to one another. It's tough to filter out the team efffect when a big part of defense is coaching style and a big part of coaching style is player composition. So it doesn't really surprise me that the best defenders seem somewhat concentrated on the best defending teams.

Maybe Trenton Hassell just wasn’t all that great a defender this year – players like Bruce Bowen and Artest who also take on the best opponent every night don’t get similarly hammered.

JNichols, thanks for your efforts on this. I think it’s very illuminating.

[JNichols42887]

That's very interesting stuff. How did you calculate team DCS? It seems the hardest decision is how much of a team factor do you associate to individual player ability. You chose to do half, which is probably more realistic than the way I did it (fully determined by player ability).

Also, you chose the first DCS system released in the first 82games article. I personally like the second one a lot better. Sure there are some players that are a bit off, but it helped so many guys like Tayshaun Prince that I think it did more good than harm. But hey, that decision in the end just comes down to our personal opinions and biases, so I guess there isn't a right way to do it.

I'm glad you're taking my data and running with it. I take that as a huge compliment.

-Jon

[kjb]

Jon: Finally got around to looking at your 05-06 results. Interesting stuff. Out of curiosity, what do you make of Jamison's "better than average" rating?
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[JNichols42887]

[kjb]

Another factor that might be getting picked up in your numbers is that Jamison had the best rebounding season since his rookie year in 05-06. It was his career high in defensive rebounds per 40 minutes. And that was for a bad defensive rebounding team, so those boards were fairly important.
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