I was re-reading the Celtics chapter in the new Pro Basketball Prospectus handbook (which you should go and buy!) and noticed something I hadn’t noticed before: The Basketball Prospectus crew predicts the Celtics will rank 20th in offensive efficiency. That’s 20th! Out of 30 teams!
This could not possibly be right…right? What’s scary is that whenever a team does something much better or worse than anyone expected, there is always some mathematical projection system that predicted it. (Sort of like how Baseball Prospectus predicted a major surge from the Rays in 2008 when humans just assumed they’d stink as usual). The machines always know first. (Or is that dogs?)
We all know the C’s have been the best overall defensive team through the last two seasons, but the story that receives considerably less attention is how good Boston’s offense has been. Last season, the C’s scored 110.5 points per 100 possessions, the 5th-best mark in the NBA, thanks largely to great shooting; their effective field goal percentage, which adjusts for the value of three-pointers, ranked 2nd behind Phoenix, and their 39.7 percent accuracy rate from three-point range is the 12th-best team mark since the league instituted the three-point ine in 1980, according to Basketball Reference.
That was a slight improvement from the championship year of 2008, when the C’s ranked 10th in the league with an average of 110.2 points per 100 possessions. Tenth isn’t great. But it’s a lot better than 20th. You can win titles with the 10th best offensive in the league.
So I contacted Kevin Pelton and Bradford Doolittle, the co-authors of the BP book, and asked them why their numbers were spitting out such a poor offensive rating for Boston.
The answer centered around the loss of Leon Powe, the team’s decision to give his minutes (and more) to Rasheed Wallace and the general aging of the team. Here’s Kevin: “The big differences are in offensive rebounding (from 6th to a projected 28th) and free throw attempts per field goal attempt (from 7th to a projected 26th). Naturally, replacing Leon Powe (and other minutes) with Rasheed Wallace is a factor there, given the time [Wallace] spends on the perimeter.”
Kevin adds: “Offensive rebounding makes a bit more sense, since Perkins is projected to go back near his career offensive rebound rate after an excellent year on the offensive glass. I have a tougher time explaining the drop in free throw rate outside of the difference between Powe and Wallace.”
On the one hand, this isn’t news. We’ve written a lot about ‘Sheed’s rapid decline in offensive rebounding rate and foul-drawing—and, conversely, of Powe’s insane ability to do both. (By some measures, Powe was the best offensive rebounder in the entire NBA last season). We’ve even hinted at the possibility that the team will suffer a massive drop in offensive rebounding this season—and that Shelden Williams, a statistically excellent offensive rebounder, could find himself a niche on the team as a result.
On the other hand, the notion that adding Rasheed Wallace and subtracting Leon Powe could hurt a team’s offense seems to fly in the face of everything we think we know about basketball. The numbers may say one thing, but this is Rasheed Wallace! And that guy on a plane to Cleveland is Leon Powe, a nice player to be sure, but one whose per-minute stats might look great precisely because there are so few minutes in that sample size.
Pelton acknowledges the numbers might not be able to encapsulate Sheed’s true offensive value: “I’d certainly be surprised if Boston were quite that bad on offense, especially because we’re not crediting Wallace at all for his ability to space the floor with his shooting.”
And Doolittle says his system, which the BP preview book does not use, predicts the C’s to rank 12th in offensive efficiency. That’s better than 20th, but it would still be the team’s worst mark of the Big Three era.
Is this a cause for concern? I’m not sure. On the one hand, it makes sense that a team as old at it core as Boston would suffer a decline somewhere. It also doesn’t seem likely the team will shoot the ball as well this season as it did last year.
But you know what? Rajon Rondo is going to be better. Wallace’s impact on the offensive is likely greater than BP’s numbers can understand. Glen Davis will be a solid jump-shooter all year instead of an atrocious one for 50 games and a good one for 30. Perk will improve. Ray Allen may defy normal aging trends for another season. KG will hopefully remain healthy enough to play effectively in June.
The team has already proven it can win a title finishing 10th in the league in offensive efficiency. They don’t need to be an offensive juggernaut. They just need to be good enough. And I remain confident they will be.