I have very little subjective observation of Desmond Mason's defense to fall back on. I was not a particularly devout connosseiur of Milwaukee Bucks basketball much of this decade, and I only got a few non-Kings Thunder games in 2008-09. Mason does have a solid defensive reputation, though.
What do the numbers tell us? If Mason will get a) minutes, or b) potentially starter's minutes on the basis that he brings something the team lacks, and it sure as Hades isn't individual offense because his individual offense is pretty terrible, then it must be defense, right? Has Mason been an objectively good defender lately?
* Last season with OKC, Mason had an unadjusted defensive plus-minus of -3.27, which means the Thunder's defense was 3.27 points per 100 possessions better when Mason was on the floor than when he was not. Unadjusted plus-minus is a bit tough to take, which is why we have adjusted plus-minus, computed by various folks but made exceedindly digestable by BasketballValue.com. Mason's total (offensive and defensive combined) adjusted plus-minus with OKC was +5.11, which is pretty damn good (second best to Kyle Weaver on the Thunder).
* In 2007-08, according to BV's figures, the Bucks defense was 1.56 points per 100 possessions better with Mason than without. (It should be noted the Bucks defense was still awful with the team's "best" defenders on the court -- 110 points per 100 possessions with Mason on the floor.) Mason's total adjusted plus-minus for the season was +1.07 points per 100 possessions, third best on the team (behind sub-rotation level Michael Ruffin and Andrew Bogut).
* Eli Witus works for the Houston Rockets as a statistical analyst. Before he got that gig, he ran the insightful Count the Basket. In one of Eli's projects, he took Dan Rosenbaum's adjusted plus-minus figures from the 2007-08 season and split them into offensive adjusted plus-minus and defensive adjusted plus-minus. He found that Mason finished that season with a DAPM of 2.2 -- the Bucks defense was effectively 2.2 points per 100 possessions better with Mason than without. This wedged Mason in the 71st percentile among small forwards, which is to say Mason's defense rated better than 71% of the NBA small forwards in 2007-08. (For what it's worth, by Witus's numbers, Kevin Martin rated as the league's third worst shooting guard defensively and Ron Artest rated as the league's fifth best small forward defensively. Martin was the No. 8 shooting guard offensively. Francisco Garcia rated rather poorly defensively, and Andres Nocioni rated just below average defensively.)
* 82games.com has fairly robust unadjusted on-off figures. The page for each player is rather self-explanatory: in the "on" column, there are the team statistics which stem from the minutes when the player was on the floor. In the "off" column, that's what the team did in the minutes the player was not on the floor. The "net" column registers the difference.
With Mason on the floor last season, OKC was:
- 3.4 points per 48 minutes better on defense.
- better at shooting defense by a 48.9%-52.3% margin (using eFG%).
- slightly more likely to block a shot.
- a better defensive rebounding team by a 73.8%-71.2% margin.
- slightly more likely to surrenders FTAs to the opponent.
- slightly less likely to force opponent turnovers.
But is this a product of not playing with OKC's worst defenders (who, according to defensive plus-minus were Kevin Durant and Jeff Green)? No, actually. Mason played a little over 1,000 minutes. Some 80% of those came in line-ups also featuring Durant. Nearly 75% of Mason's minutes came alongside Green. By simple deduction we can figure at least half of Mason's minutes came in line-ups which included both Durant and Green, by plus-minus OKC's worst defenders.
That also means, given Mason's favorable defensive plus-minus numbers, that in line-ups in which Mason played but Durant or Green did not, the OKC defense was better. That 20% of playing time without Durant could be against primarily bench players, but the other 80% alongside Durant is too much to ignore.
By the numbers, Mason is a good defender.
Of course, it takes more than one defender in the NBA. Unless Tyreke Evans starts and is a stunningly good defender as a rookie, and unless either Spencer Hawes or Jason Thompson makes a serious leap on defense, adding Mason to the starting line-up for defensive purposes isn't likely to make a major difference. And we haven't even discussed Mason's offensive issues, which are serious according to both box score statistics and offensive plus-minus.
We'll see how it shakes out, if Mason even starts or gets major minutes. While the numbers say he is in fact a quality defender, I'm not convinced he can shine up the Kings defense enough for anyone to notice.