Post-game Reactions

On almost every Celtic telecast, the broadcasters throw up a graphic showing how many more points per game the Celtics have given up with Kevin Garnett out of the lineup. Not a surprise.

But I was curious about something else: how much of an impact does KG’s absence have on the boards? After all, we’re talking about the best defensive rebounder of the last decade in the NBA; KG led the league in defensive rebounding percentage four seasons in a row from 2003-04 through 2006-07, and his 26.6 DRB percentage (translation: KG grabs 26.6 percent of available defensive rebounds when he’s on the floor) would place him in the top five this season.

I crunched the stats and found this:

Celtics ’08-09 overall defensive rebounding percentage: 75.7

Celtics DRB percentage in 17 games without Garnett: 73.5

There are two ways to look at this data. The first is to be surprised that the loss of one of the league’s greatest defensive rebounders has only cost the C’s two percentage points in defensive rebounding rate (and probably a little more since the last games have dragged down the overall number). This is especially so since the player getting the bulk of KG’s minutes at the four (Big Baby) has a low defensive rebounding rate for a power forward (about 13.0).

But maybe this not-catastrophic drop shouldn’t be a surprise? There’s been a lot of research–see here, for instance–showing some diminishing returns in team defensive rebounding, i.e. that the defensive team gets most rebounds anyway, so if KG doesn’t grab it, one of his teammates probably will.

On the other hand, a drop from almost 76 percent to 73.5 percent represents a significant fall down the league rankings, from a spot in the top three to almost exactly league average. So the other way to spin the numbers is to say that the loss of Garnett single-handedly transforms the C’s from an elite defensive rebounding team into an average one.

I’m not sure which interpretation is right, but I hope it’s irrelevant come playoff time.

But what about offensive rebounding?

Celtics overall offensive rebounding rate: 27.9 percent

C’s ORB rate without KG: 28.5 percent

So the Celtics lose KG…and improve a tiny bit on the offensive glass? This isn’t necessarily a big surprise. Throughout his career, KG has never been a top-of-the-league offensive rebounder. Starting with the ’01-02 season, KG has cracked the NBA’s top 20 in offensive rebounding rate just three times–and barely. He finished 19th in ’01-02 (9.0 percent), 20th in ’04-05 (9.5 percent), and 16th in ’05-06 (8.9 percent).

Note: This obviously doesn’t mean Garnett is a bad offensive rebounder. He’s ranged from really good in his prime to about average for a power forward over the last three seasons. Further note: that kind of fall off is not atypical for aging power forwards, and it doesn’t necessarily mean KG is a mediocre offensive rebounder. It could mean he’s playing on a team that concentrates more on getting back in transition defense than crashing the offensive glass (the C’s were 18th in offensive rebound rate last year grabbing about 26.6 percent of their misses, but they’re up to 9th this season at 27.9 percent), or KG could just be conserving his energy in a way he feel best helps the team.

One bright spot of all this: the emergence of Perk as an elite rebounder. Check out the leader boards: Perk is 19th in individual defensive rebounding and fifth in offensive rebounding. The Beast has Arrived.

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Zach Lowe

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