CelticsBlog asked the two most important questions facing the Celtics, and maybe the entire NBA, on the same day this week:
2) Is KG healthy?
Where the Celtics figure in the first conversation depends a lot (entirely?) on the answer to the second question.
But how much?
We all heard how the Celtics gave up about 10 points per game more without KG last season, but we can do better than points per game, which doesn’t account for pace of play and other variables. It’s more accurate to look at defensive efficiency, a measure of how many points a team allows per 100 possessions. Here’s how the Celtics did in 2008 and in various stages of last season. I calculated the data on a game-by-game basis using Basketball Reference’s formula for possessions.
2008 regular season Defensive Efficiency: 98.9 points allowed per 100 possessions
2009 regular season overall: 102.3 points allowed/100**
2009 regular season without KG: 109.8 points allowed/100
First round vs. Chicago: 105.9 points/100
Eastern Conference semis vs. Orlando: 108.2 points/100
**Note: I got some flak for pointing out that the Celtics offense performed better, at least statistically, in 22 regular season games without KG, even though I argued that performance was a fluke and didn’t last into the playoffs. Consider this my recompense.
So, yeah. News flash: The team can’t really play defense all that well without Garnett. But the difference is even bigger than I think most fans understand—and certainly bigger than I had anticipated, considering the general perception that the team’s defense performed solidly in the playoffs.
The Celtics 102.3 defensive rating was 2nd best in the league during the regular season, behind only Orlando. That 109.8 rating the team recorded in 22 games without KG? That would have ranked 22nd in the NBA, right behind the Grizzlies. The 105.9 rating they put up against Chicago would have ranked in the top 10 over the course of the season, and their defensive efficiency against Orlando was about league average.
How important is defensive efficiency? It may be the best overall predictor of team success. Last season, the 16 teams that made the playoffs all ranked in the top 18 in defensive efficiency, according to Basketball Reference.
We can conclude for sure that the Celtics did two things worse without KG:
• Their defensive rebounding dropped from super-elite (grabbing about 76 percent of available defensive boards) to league average (about 73.5 percent). We’ve covered that here.
• Teams shot the three better against Boston. In 22 games without KG, C’s opponents shot 37.5 percent from deep (143-of-383). That’s up from a season average of 34.9 percent—and that’s the difference between ranking fourth and 20th in the NBA. (Of course, overall shooting opponents shooting percentages also shot up without KG roaming around).
So when people try to draw comparisons between the Celtics losing KG and, say, the Lakers losing Andrew Bynum, just show them these numbers. Because few players in the history of the game have the kind of defensive impact that KG does, even when he’s dealing with bone spurs in his knee.
On the flip side, the Celtics are only a semi-relevant basketball team this year, in a macro sense, if KG isn’t healthy. So let’s hope all of those staple-related reports are wrong.