In the regular season the Celtics scored 107.4 points per 100 possessions while only allowing 96.4. The team’s efficiency differential – offensive efficiency (107.4) minus defensive efficiency (96.4)-of 10.95 was the best mark since the Chicago Bulls differential of 13.00 and 11.61 seen in 1995-96 and 1996-97 respectively. In fact, other than these two Chicago marks, the Celtics mark in 2007-08 was the best since 1973-74 (the first season we can calculate efficiency differential).
Such a performance led me to label this team the best Celtics team in franchise history. Given the 16 titles won in Boston history, I clearly believed (as did many others) that the Celtics would coast to an NBA title.
Boston in the Playoffs
And then the playoffs started. In the post-season the Celtics have scored 105.2 points per 100 possessions while allowing 99.0. In words, Boston’s offense -relative to the regular season – has declined. And their defense has worsened. As a consequence, their efficiency differential in the playoffs is only 6.23. This is still an excellent mark, just not nearly as good as what we saw in the regular season.
So what happened?
For an answer, let’s turn to Wins Produced. Table One reports what the Celtics could have expected in their first 14 playoff games had the player’s performance not changed from the regular season. It also reports what we have actually seen in the post-season.
The expectation going into the playoffs is that the Celtics would easily dispatch Atlanta and the winner of the Cleveland-Washington series. Both Atlanta and Cleveland had negative efficiency differentials in the regular season, and even with Cleveland’s major mid-season trade, one should not have expected the Cavs to contend with a team boasting a 10.95 efficiency differential.
Again, though, this is not the team that Cavs (or Hawks) ended up facing. When we look at the performances of the individual players we can see which players are primarily responsible for Boston’s drop-off. And those players are Paul Pierce, Leon Powe, and Ray Allen. As Table One reveals, these three players account for 75% of the Celtics post-season decline.
The decline of Pierce, Powe, and R. Allen
So what happened to these three players? That question is addressed in Table Two.
Table Two reports what each player did – per 48 minutes – in both the regular and post-season. Post-season marks in red are statistics that have declined from what we saw in the regular season. The fact that the table just bleeds suggests that these three players have just gotten worse with respect to everything.
But that’s not quite the case. Some aspects of performance are much worse than others. At the bottom of the table the change in the player’s production is divided into scoring, net possessions, and BLK-AST-PF. For Piece, 52% of the decline in his per 48 minute Win Score can be attributed to declines in factors associated with scoring. For Powe we also see a substantial decline in scoring (46.5%), but an even bigger decline in net possessions (55.6%).
And then there is Ray Allen. Ray Allen seems to be the player people target the most in looking at the Celtics post-season woes. His overall decline, though, is not quite equal to what see from Pierce or Powe. Still, he is playing worse. And from Table Two we see that 90% of his troubles are associated with scoring.
It’s important to note that if Ray Allen returns to form, the Celtics will improve. But not as much as they would if Pierce or Powe returned to what we saw in the regular season. Yes, the hero of the second round game seven and a little known reserve may have to step up even more than the much abused Allen for Boston to return to form.
The Pistons Close the Gap
Does all this mean that the Pistons have closed the gap? In the regular season the Pistons had an efficiency differential of 8.17. In the post-season this differential has declined to 5.10. Yes, the Celtics still boast a better differential even when we compare just the post-season performance of each team.
One should note, though, that the Pistons have faced better competition than Boston. So one could argue that the Pistons have closed the gap. Certainly as a Pistons fan I hope this is the case.
Had the Pistons maintained their regular season performance we would not have to discuss strength of competition. If that were the case the Pistons would have thus far surpassed the Celtics. Why were the Pistons unable to maintain what we saw in the regular season? One answer, as detailed in The Wages of Wins, is that playoff performance tends to be worse than the regular season (due to improved competition). One Piston, though, has decline a bit more than we would expect.
As Table Three reveals, virtually all of Detroit’s decline can be attributed to Rasheed Wallace. In the regular season his WP48 [Wins Produced per 48 minutes] was 0.142. In the post-season his mark is only 0.031.
Wallace is not the only one whose performance has changed. Chauncey Billups is also offering less while Tayshaun Prince is now leading the team in Wins Produced. If Wallace and Billups can return to form, and Prince keeps producing, the Pistons might just advance to the NBA Finals. And if that happens, I think the Pistons might just win their fourth NBA title. Or to put it another way, I think the winner of the Celtics-Pistons series should be favored over either the Lakers or Spurs.
Let me close by noting that fans of Boston and Detroit should look forward to a great series. As I noted a few weeks ago, the current edition of each team is the best in each franchise’s history. In sum, this should be real fun (and even more fun if the Pistons win).
Our research on the NBA was summarized HERE.
Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:
Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.