PDA

View Full Version : Defensive Composite Scores from 82games.com


DevinFuture
08-15-2007, 12:24 PM
It was posted on 82games.com two weeks ago, but I hadn't seen it posted here and I thought it was interesting. The ratings for every player in the league are also listed.
http://82games.com/nichols2.htm
Spurs with 3 in the top 10. Devin at #10. Przybilla at #2?
The system obviously has limitations as the guy mentions, but it's still kind of interesting to see a metric that quantifies defense like this.


As I mentioned when I first released the stat I have developed called Defensive Composite Score, it was very much a work in progress. Iím not one to assume that my ideas are better than others, so, after listening to e-mails from readers and ideas from the good people at the APBRmetrics message board (see http://sonicscentral.com/apbrmetrics/index.php), I made a few changes to the statistic. In my opinion, itís better than itís ever been and it passes the ďlaugh testĒ better than ever before (although the importance of that is debatable).

The biggest change that was made was getting rid of the method of ranking the players. While this was a simple way of doing things, it did not make it clear how close or far apart some players were. Player A was better than Player B but worse than Player C, and thatís all you knew. But by how much? Instead, the new DCS is based on z-scores (thanks to reader Dave Elkin for the idea). The only downside to this is that the ratings are not on a simple 0-100 scale. However, itís still very possible to understand what a playerís rating truly means (more on this later).

Another major change was the removal of the box score stats completely. The three stats used were blocks, steals, and foul efficiency. Unfortunately, those stats donít tell us much and can be very deceiving. I replaced the box score section with the counterpart PER statistics that can be found here at 82games. Because counterpart PER is generally not equal for all positions, I calculated it based on a playerís z-score within their position. Also, I consider small forwards and shooting guards to be interchangeable, so those two positions were combined.

Finally, I received a bunch of e-mails explaining how itís not fair for Player X to get a certain score because said player either plays only in garbage time or said player has to guard the other teamís best scorer every night. I tried to adjust for that by using a statistic developed at the APBRmetrics board called %St. This statistic estimates how much of a playerís minutes were against starter-quality opponents. Now, the top of the leaderboard isnít dominated by players who come in off the bench to guard lower quality opponents.

The new average for DCS is 0. Positive scores denote good defenders and negative scores mean bad defenders.

Scores of 40+: Excellent defender
20 to 40: Very good defender
0 to 20: Above average
-20 to 0: Below average
-40 to -20: Poor defender
-40 and below: Terrible defender

This statistic still has many of the same limitations as before. DCS still is no substitute for scouting out the game in person and analyzing a playerís strengths and weaknesses. It canít tell you that Trenton Hassell has the unpleasant job of guarding the Kobe Bryantís of the world every night. Hopefully it does as good of a job as statistics possibly can. Most people havenít seen every player play enough to get a good judgment of their defensive ability, so DCS is useful in this sense.
Plus-minus stats and counterpart PER were found at, of course, 82games.com. Defensive ratings, which were developed by Dean Oliver, were obtained from basketball-reference.com. And thanks to everybody at the APBRmetrics board, especially Mike Goodman, Neil Paine, and ďcherokee-ACB.Ē I also included rating percentiles (courtesy of Kevin Broom) for those wishing to see a number on a simple scale.

Here is the top 10 overall followed by the complete list:

TOP 10 OVERALL
PLAYER DCS
Tim Duncan 73.0
Joel Przybilla 61.5
Bruce Bowen 58.4
Yao Ming 57.0
Manu Ginobili 56.3
Kevin Garnett 54.5
Zydrunas Ilgauskas 49.9
Tyrus Thomas 48.5
Jermaine O'Neal 48.0
Devin Harris 47.6


In the table below you can see these ratings for every player, sorted by team and DCS.

If you love this stat, hate it, or just want to tell me how you feel, e-mail me at jn42887@bellsouth.net

ABOUT THE AUTHOR
Jon Nichols is a junior Sport Management major at the University of Michigan. He has written articles for NBADraft.net, CourtsideTimes.net, and Hoopsanalyst.com. When not at school he lives in Miami and is a huge Heat fan.

Player Team Pos Def.+/- Drtg Counter Part DCS Rating Percentile
harris,devin dal PG -8.6 104 15.0 47.6 97.2%
dampier,erick dal C -4.4 102 17.2 39.3 93.5%
nowitzki,dirk dal PF +1.7 102 13.1 34.6 91.1%
howard,josh dal SG/SF +1.0 102 13.0 30.8 89.6%
terry,jason dal PG +1.9 106 14.8 13.8 73.7%
diop,desagana dal C -1.3 98 19.1 8.2 65.1%
george,devean dal SG/SF +1.0 103 15.3 3.5 57.1%
stackhouse,jerry dal SG/SF +2.6 106 13.8 -4.9 43.7%
croshere,austin dal PF -3.2 102 20.8 -10.5 35.7%
buckner,greg dal SG/SF +3.3 105 16.8 -21.1 16.8%

Flacolaco
08-15-2007, 12:29 PM
nowitzki,dirk dal PF +1.7 102 13.1 34.6 91.1%
howard,josh dal SG/SF +1.0 102 13.0 30.8 89.6%

According to this...Dirk is a better defender than Josh?

DevinFuture
08-15-2007, 12:35 PM
Correct. And anybody who follows the Mavs knows that's wrong. Josh often has a tougher defensive assignment, and that's one of the things this metric doesn't ajust for.

alby
08-15-2007, 10:11 PM
Josh is an overrated one on one defender.

He definitely deserved all the praise his rookie year, but since becoming more involved and focused with his offensive game--he has not nearly come close to his potential on the defensive side of the ball. Not even close.

MFFL

V2M
08-15-2007, 10:38 PM
To me Josh and Dirk are both decent, above-average defenders. In the media though, one is over-rated and the other, under-rated!

Of course, as always, this board knows better!

alby
08-15-2007, 10:58 PM
Of course, as always, this board knows better!

Was this sarcasm?

Some people here think Howard should be a defensive first teamer...

Flacolaco
08-15-2007, 11:07 PM
nash,steve pho PG +0.9 110 16.2 -0.4 52.5%

nowhereman
08-16-2007, 12:43 AM
there's a clear big man bias in that top 10.

alby
08-16-2007, 03:51 AM
our big defensive free agent signing of last year, Greg Bucker = 16%

AxdemxO
08-16-2007, 06:50 PM
Dirk is not a good defender..I love the guy but he just is not...he makes plays here and there but who doesnt...Josh is better ..not great but getter then Dirk