Tuesday, May 20, 2014

NBA Player Consistency

Last week I blogged about NHL goalie regular season production consistency.  I only included goalies who started a minimum of 10% games played in consecutive regular seasons.  Now I am turning to NBA players using the regular season data from those NBA player stat gurus at boxscoregeeks.com.  Here I am looking at players who have played a minimum of 10% of regular season minutes (approximately 394 minutes) in consecutive regular seasons from the 2012-13 and 2013-14 NBA regular seasons.

How is consistency measured?  Previously I stated for MLB batters that, "...consistency is measured by where they rank in terms of runs created in a given season.  For simplicity in The Wages of Wins, we took a player who was in the top 20% of the league in runs created as having a rank equal to 1, the next highest 20% with a rank of 2, all the way to the lowest 20% with a rank of 5.  If a player maintains their rank from one season to another they are considered to be consistent and if not, they are considered to be inconsistent."

When I run the NBA player consistency analysis (step-by-step guide here), I find that there are 287 NBA players that have played at least 394 minutes in both seasons and of those 287 NBA players, 45.6% of those players have keep their same "grade" in each season.  Additionally, another 34.5% of NBA players move up or down only one "grade" from season to season, leaving about 19.9% of NBA players moving two or more "grades" from the 2012-13 season to the 2013-14 NBA regular season.  This is similar to what we found in The Wages of Wins (see the end of chapter 9).

There were 131 NBA players that were consistent in consecutive seasons.  Of those, 34.35% were in the top 20% of the distribution (or "A grade" player production), while 19.08% were "B grade" players, 13.74% were "C grade" players, 16.79% were "D grade" players and 16.03% were in the bottom top 20% of the distribution in consecutive seasons.

For those who read Dave Berri's piece on John Wall, he is a consistent "B grade" player.