Friday, November 7, 2014

Kobe: Career 50 Game Moving Averages

After the most recent 14 for 37 shoot-first-ask-questions-last loss, I started thinking that 2014 Kobe might simply be a bad player that gets to shoot a lot. In other words, offensively, he produces what any marginal NBA player would given the green light to shoot the ball 30+ times a game. But I wanted to understand if the data supported this perception. There are countless approaches to measuring this, and the greatest challenge of measuring my perception of Kobe's contemporary futility is that he has only played 11 games over the last two seasons so I'm dealing with an admittedly small sample size to account for 'current' performance.

One way to address this is to create a moving average of his past performance. I pulled all of Kobe's regular season game logs from and included only games in which he appeared (as of his last game on Tuesday night, Kobe has appeared in 1,250 regular season games). The benefit of a moving average is that it smooths performance (in this case over a 50 game period) so anomalously exceptional or futile performances are regressed to the mean of the 49 previous games.

To create the moving average I don't report Kobe's first 49 games because "game 1" is essentially the mean of his first 50 games. ("Game 2" is the mean of games 2 through 51, "game 3" is the mean of games 3 through 52, etc.) I created a moving average for FG%,  assists, points, total rebounds, and steals (all plotted below). I also included his career regular season average in each of those categories to provide some context. What does it show? First, that it took Kobe a few years to adjust to the NBA game as he has a sharp increase in every category for his moving average games 0 to about 400. This is expected as he was drafted out of high school and he received significantly less playing time his first three seasons.

If Kobe was truly becoming an ineffective player then we would expect each chart to show somewhat of a bell curve where the plot rises from early-career inefficacy to a mid-career peek and then drops to reflect a current state of inefficacy. But that doesn't happen. For the most part Kobe is right around his career average in these conventional statistics with the exception of assists where he is becoming much more prolific relative to the rest of his career.

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