As discussed during yesterday's NBA Finals previews, one of the key storylines entering this series is just how well the Boston Celtics have played in the postseason, knocking off a pair of elite teams in the Cleveland Cavaliers and the Orlando Magic and doing so in convincing fashion.
To quantify that success, we can turn to the method I've used in the past--a comparison of a team's playoff performance with what we would expect an average team to do against the same opposition based on regular-season performance. When we last took a look at this entering the conference finals, the Magic had been the dominant team of the postseason despite playing a weaker slate of opposition than the Celtics.
As it turned out, that advantage was enough that Orlando still ranks as the best playoff team despite its loss in the Eastern Conference Finals.
Team Diff Comp Rating
Orlando 12.1 5.6 17.7
Boston 5.4 7.2 12.6
L.A. Lakers 4.8 5.1 9.9
Phoenix 4.3 4.9 9.1
The first figure is the team's playoff efficiency differential, where the Magic still has an enormous lead. The second number is the regular-season differential of opponents, weighted by number of games in each series. Here it's clear that the Celtics played the most difficult schedule, though the difference isn't enormous. The two numbers added together show how much better than an average team each conference finalist has played during the postseason on a per-100-possessions basis.
There is a precedent for a vanquished team leading the league. Last year, the Cavaliers followed a very similar script in sweeping their first two series before losing in the Eastern Conference Finals, while the Denver Nuggets actually had the best playoff rating of any team. Still, Boston's rating is very good. To put it in historical context, let's take a look back at the last decade using the ratings I compiled to rank the best teams of the 2000s. The method there was slightly simpler, using point differential instead of efficiency differential and just taking the average of all opponents instead of weighting by games.
Here are the top teams since the 2000 postseason by this measure.
Year Team Diff Comp Rating
2001 L.A. Lakers 12.8 5.5 18.3
2009 Denver 8.6 3.7 12.4
2010 Orlando 8.7 3.2 11.9
2009 L.A. Lakers 7.2 4.2 11.4
2009 Cleveland 8.5 2.6 11.1
2010 Boston 5.2 5.4 10.6
2010 L.A. Lakers 4.0 4.6 8.6
2010 Phoenix 4.6 4.8 9.4
For whatever reason, looking at the playoffs this way has rewarded teams that fell short of a title. In part, by adjusting for strength of schedule, we're hurting favorites. If two teams play even over the course of a series, the weaker one will look better here, which is accurate on some level but not exactly what matters for history. More than that, what we've seen the last two years in particular is that beating up on weaker competition in the early rounds has not translated once the level of opposition increases.
What makes the Celtics unique, then, is that they've built their rating the opposite way--winning consistently against elite teams. So far, their opposition ranks as some of the hardest faced by any team to reach the conference finals in the 2000s, though the fact that Cleveland's point differential was lower than we'd expect from a 61-win team hurts Boston a little bit here.
Year Team Comp
2008 L.A. Lakers 6.4
2009 Orlando 6.0
2001 L.A. Lakers 5.5
2010 Boston 5.4
2008 Detroit 5.4
The 2008 Lakers knocked off three teams with 50-plus wins in a balanced Western Conference before losing to Boston in the Finals. Last year's Magic dealt with two titans, beating Cleveland in the Eastern Conference Finals before losing to the Lakers. The 2001 Lakers are perhaps the most impressive playoff team in modern history, having not only faced a challenging set of competition (at least in the West; Philadelphia was a relatively weak NBA Finals opponent) but beaten them by 12.8 points per game, far and away the best playoff point differential in our study.
Because the Lakers, like the Cavaliers, were unimpressive in terms of differential in the regular season (+4.7 points per game), the Celtics' level of competition rating will actually slightly drop after this series. Still, if Boston defeats teams with regular-season totals of 61, 59 and 57 wins to claim the championship, it will be an impressive feat--especially for a team that went a disappointing 50-32 in the regular season. The other way we can look at these numbers is to see which teams most outperformed their regular-season efforts.
Year Team Reg PO Diff
2001 L.A. Lakers 3.4 18.3 14.9
2009 Denver 3.4 12.4 9.0
2010 Boston 3.7 10.6 6.9
2003 San Antonio 5.4 9.6 4.2
2009 L.A. Lakers 7.7 11.4 3.7
In the past decade, we've only seen a couple of teams turn it on for the postseason to a degree comparable to this year's Celtics. The 2000-01 Lakers were nicknamed "Team Lightswitch" because their motivation was so uneven during the regular season before they started crushing teams in the playoffs (in fairness, health was also a key factor in the mediocre regular-season results). Last year's Nuggets benefit from a 58-point win over the New Orleans Hornets in the first round, but also played the Lakers far closer during the Western Conference Finals than the teams' regular-season numbers portended. Beyond that, we have a couple of champions who took their play to the next level after solid regular seasons, which is nothing all that out of the ordinary.
That the runs made by the 2001 Lakers and Boston this year stand out remains true even if you look at a much longer period of time. Using a slightly different method and focusing solely on teams that reached the NBA Finals, Neil Paine found today at the Basketball-Reference.com blog that the two teams stepped up their performance in the preseason more than anyone else.
Stay tuned all week for Basketball Prospectus' coverage previewing the 2010 NBA Finals. On Thursday, join Kevin Pelton for a chat at BaseballProspectus.com starting at 1 p.m. Eastern.
Kevin Pelton is an author of Basketball Prospectus.
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