Attached are John Hollinger’s Player Efficiency Ratings (PER) for 2009. If you want to know more about PER ratings, you might want to the Wikipedia article about PER and how it works.
PER is an “all-in-one” metric and has the faults of an all-in-one metric. Whenever you try to describe a player using one numerical stat – even if that stat purports to sum up all that player accomplishes – there is the danger of losing information. Metrics suffer from what I call the “gamer’s dilemma” – the fewer numbers, the greater the chance of losing information; the more numbers, the more complex and unwieldy the metric.
There are other problems with PER. It doesn’t measure defensive statistics very well, but no basketball metric does. It is not an additive metric, which means that player who played limited minutes have a chance of scoring a very high PER. (See Sherill Baker.) It also rewards inefficient shooting.
So what’s good about PER? First, PER takes into account individual team paces as well as how well players and teams perform against the WNBA average. Teams with a fast pace like the Mercury can’t stack up points the way they would in an additive metric.
Furthermore, it’s easy to understand. The league average player has a PER of 15.00. This is a deliberate choice; all PER ratings are normalized to force the league average player to be at 15.00. There is also a scale that Hollinger provides for PER:
A year for the ages: 35.0
Runaway MVP candidate: 30.0
Strong MVP candidate: 27.5
Weak MVP candidate: 25.0
Bona fide All-Star: 22.5
Borderline All-Star: 20.0
Solid 2nd option: 18.0
3rd Banana: 16.5
Pretty good player: 15.0
In the rotation: 13.0
Scrounging for minutes: 11.0
Definitely renting: 9.0
Next stop: Latvia: 5.0
So what can PER tell us about the 2009 season?
Sherill Baker – who played one game – is not the very best player in the WNBA this year. Baker shot 2-for-3 in her lone game and PER rewards her greatly. You have to keep in mind that PER only means something if the player has a lot of minutes.
Seimone Augustus’s injury hurt the Lynx a lot. If Augustus could have kept that 30+ PER all season, it would have been one of the WNBA’s great seasons. Only eight WNBA players have managed a PER of 30+ while also playing significant minutes. The best? Lauren Jackson’s PER of 34.72 in 2006.
Furthermore, the argument could be made that Jackson deserved the MVP over Taurasi. However, Taurasi played more minutes than Jackson (976 vs. 843) and also played the Mercury to a WNBA title. Despite Jackson’s higher rating, the MVP voters made the correct decision.
Who was the real Rookie of the Year? If you believe PER, it’s Angel McCoughtry, who makes it to the Top 10 in players with significant minutes.
You can even judge – or try to judge – trades if both players played enough minutes. Take the Tamera Young/Armintie Price trade. One problem with PER is since that it’s based on performance relative to team/league, a player can have two different PERs if they played with two different teams. (I suppose you could weight each component PER by minutes played on each squad and built an overall PER for the player.)
Before the trade, Young had a 12.05 PER with the Dream and Price had a 10.48 PER with Chicago. They seemed to be fairly equal players. Afterwards, Young’s PER went up to 14.34 during her time with the Sky. Price’s PER, on the other hand, collapsed to 4.23 with the Dream. There were considerations other than talent that necessitated that trade – Young and her agent essentially forced the trade – but the trade was more of a bonus to the Sky than it was to the Dream.
So here are the 2009 Player Efficiency Ratings. If you have a problem with the results, don’t call me – call John Hollinger. I hear he’s on Twitter!