Mandatory Credit: Kyle Terada-USA TODAY Sports
The first quarter or so of the season is over so I decided it was enough data to at least run my Player Tracking Plus-Minus metric, which is a statistical plus minus using SportVU data[1. The independent variable was the RAPM score via GotBuckets for 2013-2015 for all players with more than 500 minutes in a weighted least squares regression using an AIC stepwise filter and cross validated for stability.]. You can read more about its development, on the offensive side here and original version here. Because there is only one full year of SportVU data that is public, it is best to consider this project a beta test to see how the new data fits with traditional box score data and what we know about basketball. Though, it is worth noting, maybe, that my win predictions for this season using PT-PM was leading the APBR prediction contest through the first quarter of the season.
Of course, it’s also a new way to look at player performance, and everyone who can’t see the Russian financial meltdown from their back porch seems to like player rankings, I thought I would start out with a top twenty lists at this point[As of Dec 15, 2014].
I used a fairly arbitrary 350 minutes of playing time minimum. Most of the names on the list, topped by Steph Curry and Anthony Davis are the ones anyone following the NBA this year would expect. Then there’s Darrell Arthur, Ersan Illyasova, and Rudy Gobert, who safe to say, are not among the top twenty players in the league. That mostly speaks to the noisy nature of the data at this point. Curry, for example, has “held” opponents to 36% on shots he has contested, which is not a trend I would expect to continue.
Of course, one name is very notably absent, LeBron James. James comes in 31st, his offense is elite but not transcendent, while his defense is merely average. (Kevin Durant and Russell Westbrook didn’t have enough minutes played coming off of the injury). Below are the scores for all of the Cleveland Cavaliers with over 350 minutes
We can see that James has struggled with extending and retaining offensive possessions, with his turn overs up and offensive rebounds down, and while his scoring is well above average it is down from his previous seasons. Meanwhile Kyrie Irving has pretty clearly been the team’s second best player.
In reality, the first quarter check in is really a first opportunity to assess how well the metric is performing out of sample. For example, I plan to run a some comparisons with other metrics, as wells look at the performance on both ends of the court on a team level.