Earlier this week I blogged about how consistent NBA players were from the 2012/13 regular season to the 2013/14 regular season. What I found is that compared to players in other leagues, NBA players are much more consistent. We also report this for a number of seasons in chapter 9 of our book, The Wages of Wins. I got to thinking about whether this result holds over a longer period of time, and asked Dave Berri if he would send me the data, which he graciously did. Dave's NBA player data starts with the 1973/74 regular season and goes up to the 2013/14 regular season, which for those keeping track is over forty years of player data.
So, just as I did earlier this week, I ranked all the players (see link above for the details) and look at players who played in consecutive regular seasons playing at least 10% of the total regular season minutes (having adjusted for the 1998/99 and 2011/12 shortened seasons). What I find is that 42.1% of all the players who played at least 10% of total minutes in consecutive regular seasons are consistent (i.e. are in the same quantile), while 39.2% either move up or down one quantile from one season to the next; meaning that only 18.7% of NBA players are very inconsistent over consecutive seasons.