Defense for the big men: what do the adjusted plus/minus ratings say?Defense for the big men: what do the adjusted plus/minus ratings say?
By Dan T. Rosenbaum
If I had a dime for every time I heard that you can't measure defense with stats, I would be a rich man. (Well maybe not rich, but I might have enough money for a nice dinner.)
Steals, blocks, and defensive rebounds - they give us only a snapshot of what a player does on defense. We would like to have more and better data to measure defense. One direction is to collect better defensive statistics, an effort that is being spearheaded by Roland Beech at 82games.com.
Another approach is to use plus/minus statistics to measure how a team defends when a player is in the game versus when he is not. It would seem odd to say that a player was a good defender when his team defended better when he was on the bench than when he was in the game.
Now, of course, it is important to account for who a player is playing with and against. Playing beside Ben Wallace might even make me appear to be a good defender. For that reason I compute adjusted plus/minus ratings that account for who a player is playing with and against. These adjusted plus/minus ratings can then be broken down into their offensive and defensive components.
In "Measuring How NBA Players Help their Teams Win" I describe the gory details of how I compute these adjusted plus/minus ratings. (I have made a few changes since then, along with adding another year of data.) It takes a lot of data for adjusted plus/minus ratings to tell us anything useful and for that reason it is useful to ask another question. What is the average adjusted plus/minus rating of players similar to a given player? Answering this question can give me a second estimate of a players' defensive productivity and help combat errors from adjusted plus/minus ratings due to lack of data.
So combining ratings of defense from a players' own adjusted plus/minus rating and that of players similar to him, which players are the best defenders? I list the best and worst by position among players playing 1,000 or more minutes in 2004-05. These ratings are predictions for the 2005-06 season assuming that younger players will improve their defense and older players may see a decline in their defense.
Top Five Centers:
Ben Wallace
Dikembe Mutumbo
Theo Ratliff
Jason Collins
Joel Pryzbilla
Bottom Five Centers:
Primoz Brezec
Marc Jackson
Predrag Drobnjak
Mark Blount
Eddy Curry
Ben Wallace by all accounts is a game changer as a defender, so it is comforting to see him at the top of this list. Wallace is joined by three of the top shot blockers in the league in Dikembe Mutumbo, Theo Ratliff, and Joel Pryzbilla. Jason Collins has consistently over the past three seasons had an above average adjusted plus/minus rating and the reason is because he is a very solid defender.
Primoz Brezec was a solid offensive player for Charlotte last season, but his poor defense resulted in the Bobcats playing worse when he was out on the court. Eddy Curry also has consistently had a below average adjusted plus/minus rating over the past three seasons, and the biggest reason is his poor defensive play.
Interestingly, Kurt Thomas who was recently acquired by the Phoenix Suns rates in the bottom third among centers in defense. It is rather surprising to hear analysts argue that a players who made the 5th worst defense (the Knicks) worse is going to help the 17th best defense (the Suns) get better.
Top Seven Power Forwards:
Tim Duncan
Kevin Garnett
Nick Collison
Tyson Chandler
Nenê
Andrei Kirilenko
Rasheed Wallace
Bottom Seven Power Forwards:
Matt Bonner
Cliff Robinson
Antawn Jamison
Juwan Howard
Austin Croshere
Antoine Walker
Shareef Abdur-Rahim
I am sure no one will be surprised to see Tim Duncan and Kevin Garnett at the top of the list on defense for power forwards. Nick Collison is a bit of a surprise to anyone who did not watch the Sonics play a lot. (Please note that with just one year of data, ratings for rookies like Collison are more prone to error.)
I am sure many will be surprised to see Cliff Robinson in the list of worst defensive power forwards, but last season he had a dreadful adjusted plus/minus rating. Both Golden State and New Jersey played better defense when he was on the bench.
It is time for bed now, so I will leave the other positions for the next installment. But as a sneak preview, there will be a player who is about to receive a maximum salary offer who will rate as the worst defensive player at his position. Can you guess who that might be?
