This spring I began researching a paper analyzing the effectiveness of the NBA draft. The paper is still in the process, but I want to share some of my findings and hopefully garner some responses/comments.
My thesis is that the NBA’s amateur draft is intended to allocate new talent to teams that need it most. If it is effective, then there would be some fluctuation of teams transforming from bad to good. Essentially, a cycle would turn bad teams into good teams by allowing them first crack at young talent. My first data analysis consisted of determine if there is a lag to each team’s success. I thought that if the draft was effective, teams that were bad in the past would be better 5 or so years later- once their prospects had developed. That is, the question I asked was: Were the teams that are winning now losers 5 years ago. Here is a table of winning percentages for the top four teams in each conference:
For the 2009-2010, there was a significant negative relationship between wins in 2006 and wins in 2010 (the 2010-2011 year had not finished when I last worked with the data). But, there was no correlation between wins in 2009 and a year 5 or so year in the past. Using a time-series analysis on team’s wins over the past 25 NBA seasons, I found that the only significant predictor of a team’s current number of wins was the previous year’s number of wins. That is, teams that are winning now were not statistically significantly worse 5 (or so) years in the past. My conclusion was that the NBA’s amateur draft does not turn losing teams into winning teams.
One additional conclusion I came to was that certain draft classes do matter. Specifically, I found that the draft classes of 1987, 1998, and 2003 turned losing teams into winners 7 years later. Each draft class turned some losing teams into significant winners. While only serving as anecdotal evidence, Lebron James turned the Cleveland Cavaliers from a 17 game winner in 2003 to 61 game winners in 2010 and from the draft class of 1998 both Dirk Nowitzki and Paul Pierce turned struggling teams into winners in the early 200s.
My next thought is to account for draft pick number rather than losses, since the lottery does not ensure a reverse order. There are some interesting studies on the NBA draft including “Losing to Win” by Beck Taylor, which analyzed if teams intentionally lose games in a “race-to-the-bottom” in order to arrive at the top pick.
Most analyses assumes that the NBA draft works, but my research points to an ineffective process of allocating rookie talent to the teams that need it most.