That stat really jumped out. That doesn't seem to be something you could explain except that Blair isn't getting it done on the glass.
Still, I had the Portland game recorded, so just for laughs I watched the whole thing for the plays where Blair was on defense. His rebounding, in and of itself, didn't look that bad. But I did notice that he spent a lot of time away from the basket, on Aldridge, and that he switched several p&r's that left him out of position for rebounding. There were a few plays, though, where it looked like he was content to just stand and watch.
So I thought, hey - the big problem with Blair missing defensive boards would be if the opponents are getting offensive boards, right?. (Maybe not the only problem, but the one that hurts the score.) Because if Blair misses a defensive rebound opportunity to a teammate, that's not such a bad thing. That made me wonder: of the offensive boards that the opponents are getting, what percentage are they getting with Blair in the game?
I went back 5 games worth of play-by-plays. (Then I had to take a break.) But here's what they showed.
Phoenix: Blair was in 66% of the time. The Suns got 60% of their offensive boards while he was in. (6/10)
Portland: Blair was in 58% of the time. Portland got 60% of their offensive boards while he was in. (6/10)
Houston: Blair was in 33% of the time. Houston got 20% of their offensive boards while he was in. (3/15)
Milwaukee: Blair was in 50% of the time. Bucks got 71% of their offensive boards while he was in. (*5/7)
OKC: Blair was in 38% of the time. OKC got 29% of their offensive boards while he was in. (2/7)
*Against Milwaukee, the Bucks got 3 offensive boards on a single play. One of those maddening episodes where the Spurs just can't corral the ball, and the other team keeps missing the putbacks. The rest of the time, Blair really wasn't missing out on an excessive number of available defensive boards.
Between watching the one game, and looking at all five play-by-plays, here are a few things that stood out about Blair's rebounding:
1. Blair just loses focus from time to time. Sometimes he doesn't go after a rebound when it looks like a teammate has it corralled, or when it looks like an "obvious" made shot by the opponent. Then when the ball bounces out, he's standing in no man's land, watching. Those are the real problem cases.
2. A lot of the offensive boards given up when Blair is in the game happen right near the end of quarters, and during garbage time. It looks to me like Blair has already mentally gone to sit down, rather than finishing strong. When you're dealing with relatively small samples, a few plays like that can really skew the numbers. I didn't see any of them that actually hurt the Spurs, but that doesn't matter.
3. It looks to me like he's spending a lot more time this year defending guys like Scola and Aldridge, away from the basket. Sometimes he's out of rebounding position because of bad defense earlier in the play. Sometimes he legitimately can't get back, and those boards are the responsibility of his teammates. Blair's rebounding depends on being under the basket and rooting for position. When he's away from the basket and trying to crash inward, the taller guy is going to get it a lot more often.
Bottom line - I don't think the problem with Blair rebounding is his knees. It's his head. Partly because his head isn't in some plays, and partly because his head is too close to the ground. I'm sure his teammates are covering up for some of his off plays. But for the most part, the Spurs' opponents aren't getting extra offensive boards when Blair is in the game vs. when he is out.
I don't know if it looks different, further back. My eyes are bleeding from combing through five play-by-plays. One thing I do wonder about the stats on 82 games is what all they include - small samples and all that. For instance, a shot blocked by Tim that goes to an opposing player counts as a missed shot, and an offensive rebound for the opponents. A desperation shot that clanks off the iron at the last second counts as a missed shot and a missed defensive rebound opportunity. (Nobody gets a rebound.)
I know it goes against perception, but (for 5 games at least) the Spurs' opponents really aren't getting as many offensive boards with Blair in the game vs. with him out. Maybe he should still be getting more boards, and maybe his teammates covered for him. But Blair's rebounding doesn't seem to be killing the Spurs' point differential. At least not lately.