“All models are wrong, but some are useful,” George E. P. Box.
Metrics and statistical evaluation tools are never exact. Dean Oliver never claimed that using Offensive and Defensive rating would allow a MVP voter to instantly identify the precise best player in the league, much the opposite in fact. Metrics are meant to serve as one indicator of efficiency and production that can be applied against the complexities of a game with 10 men on the court at any given time employing various strategies against a shifting landscape of circumstances.
That said, metrics are useful as quick and rough single number evaluators of who the pool of players operating at the highest level may be, and journalists and fans are learning to fall back on these numbers more readily than in the past. So given that we know the metrics we rely on are not perfect, let’s take a quick look at who is left in these playoffs as an indicator of just how useful the derived numbers are.
The above table – courtesy of Basketball-Reference.com – shows the top 20 players by PER from the 2013 regular season. 7 of the top 10 (including Westbrook since he helped to win the first round series) are still in the playoffs. Of the other three in the top 10 no longer in the playoffs, Chris Paul and Brook Lopez were in their respective first round series through game 7, and Kobe Bryant missed the entire first round due to injury – though given that Tim Duncan and Tony Parker are represented in the top 10, clearly either Kobe or Tim and Tony would not be playing in the second round if Mamba had played.
Players 11-13 also played until game 7 of their series. 14 and 15 were talented young players on weak teams that missed the playoffs. 16 is Stephen Curry, the presumptive MVP of the playoffs so far, and Deron Williams rounds out the top 20 as yet another game 7 participant. Basically what we see here is that 15 of the top 20 players by PER advanced to the second round or pulled their round 1 series to 7 games, which I would suggest indicates that their teams were good enough to advance with a break or two in their favor. If you excuse the Lakers’ crummy showing due to Kobe’s injury, it’s 16 of 20. So either 75% or 80% of the top 20 players led teams good enough to win a playoff series.
Winning isn’t exactly what PER is trying to predict, but if we adhere to the old standard that winning in the NBA requires star players, we do see the players that PER considers to be stars well represented.
Unlike PER, Win Share really does aim to predict winning, and it actually does an even better job by the standards we established in the above study. Every single player in the top 20 for Win Share per 48 minutes advanced to the second round of the playoffs or made it to game 7 (again including Russell Westbrook) of the first round.
I’m both impressed and surprised by these results. I’m going to have to do a historical retrospective on this investigation and see if these two metrics pertaining to individual players have always been such accurate predictors of team playoff success.
For our purposes PER and WS/48 really do prove to be useful. Go nerds!
Tags: 2013 NBA Playoffs, Al Jefferson, Anthony Davis, Blake Griffin, blatche, Brook Lopez, Carmelo Anthony, Chris Bosh, Chris Paul, David West, dean oliver, Deron Williams, Dwyane Wade, george e p box, George Hill, James Harden, John Wall, Kevin Durant, kobe bryant, Kyrie Irving, lamarcus aldridge, lebron james, NBA, Russell Westbrook, serge ibaka, sports, Stephen Curry, tim duncan, Tony Parker, tyson chandler