Posted by Neil Paine on June 1, 2009
In the final installment of the season, here's your official Statistical +/- prediction for the 2009 Finals:
|Lakers in 4||10.6%|
|Magic in 4||2.8%|
|Lakers in 5||15.9%|
|Magic in 5||8.8%|
|Lakers in 6||23.5%|
|Magic in 6||8.8%|
|Lakers in 7||20.0%|
|Magic in 7||9.6%|
|Lakers win series||70.1%|
|Magic win series||29.9%|
One caveat is that SPM did not get a good read on the Magic in the East Finals -- while it fairly accurately estimated their odds at 53-54% against the Celtics, it greatly underestimated their chances vs. Cleveland, pegging their probability of beating the Cavs at just 18%. Then again, the 2009 Eastern Conference Finals may go down as one of the shining examples of point differential's failure to effectively predict the future under certain specific circumstances.
As John Hollinger wrote after Game 1 of the Magic-Cavs series, and as Orlando proved time and again over the subsequent 2 weeks, the Magic posed a number of significant matchup issues for the Cavaliers. What was, in retrospect, obvious during the regular season proved incontrovertible during the conference finals: the Magic were basically tailor-made to exploit Cleveland's deficiencies, with the deadly combination of Dwight Howard's inside presence and a host of expert 3-point marksmen on the perimeter. That LeBron James' supporting cast had a difficult go of things against Orlando's top-ranked D was an added bonus for the Magic, who may very well have won the series even if, say, Mo Williams hadn't shot an anemic 37% from the floor. Their advantages on offense were just too much for the Cavs to deal with, especially down the stretch in a number of games. But point differential/pythagoras saw none of this coming. Cleveland had the league's best differential, its best SRS, and yet the matchups posed by the supposedly inferior Magic spelled their doom, numbers be damned.
All of which is to say, it's not an exact science. Point differential (specifically one adjusted for strength of schedule like SRS) remains the best predictor of future performance, but it's not bulletproof -- or else we'd have all made a killing in Vegas a long time ago. Sometimes you can identify a matchup that seems significant before a series begins, but it turns out to be a non-factor. And sometimes the stats are overwhelmed by matchups. This recent Cavs-Magic series happened to be a very glaring example of the latter. I'm still going with the numbers over the next few weeks, though: Lakers prevail in 6.