Friday, July 8, 2011

Do You Believe In Plus-Minus Stats?

Among the many things I am going back and taking a look at as we begin to construct things for the 2011-12 men’s basketball season is the plus-minus from 2010-11. I actually share this with the coaching staff after every game – they had been constructing it on their own but it is now a feature of the stat program we use in our office. How much of a story it really tells is a subject of debate among basketball people everywhere.

It’s a regular feature in NBA box scores and analysis, and a few years back The New York Times referred to it as the “stat du jour” of the NBA. It has stuck and has moved into the college ranks – that’s why it’s in our stat program now – but there are varying schools of thought on how accurate it truly is.

Here is a recent NBA example. In game six of the NBA Finals, Brian Cardinal was a +18 off the bench for the Mavericks, but that was in just 12 minutes where he had three points and one assist. Brian Cardinal had a noticeable impact in the Finals, yes, but +18 in 12 minutes was hardly his doing alone. Meanwhile, in the same game, LeBron James was a -24 (insert your own analysis of James’ here).

For what it is worth, the three best regulars in the plus-minus last season for the Panthers are back for this coming season.

Tony Meier +3.88 (40 minutes - +5.50)
Kaylon Williams +1.36 (40 minutes - +1.67)
Ryan Allen +0.16 (40 minutes - +0.38)

When you begin to look at the numbers from certain games, they do match what you saw with the eye. But do you need plus-minus to tell you Kaylon was spectacular at UIC in February? That said, I would offer to you that the three players who made the most consistent positive impact in their time on the court this past season are the three on the list above. You might throw Tone Boyle and Anthony Hill in that group, too, with their respective plus-minus numbers at -0.21 and -0.98. But T Meier was clearly the most consistent contributor last year, and Kaylon easily outdid his few poor games with a laundry list of good to great performances.

This season, I will post the plus-minus on the blog throughout the season. Another feature of our stat program is to analyze the different rotations and the plus-minus while that group is on the floor. You see those stats on the PDF, as well. And, as always, there are a few things the computers do that you can’t control – like the fact Evan Richard apparently played for 25 seconds against Florida Atlantic. We know he didn’t, but there doesn’t seem to be a good way to eliminate that from this computer report. Oh well.

You can view the entire season worth of plus-minus and rotations here.