One factor that GM’s and scouts take into consideration when scouting is how ready different prospects are to play in the NBA.  For the top teams in the league with picks late in the draft, this is often crucial.  A player’s readiness is affected by his size, style of play, experience, and a number of other factors.  However, it is commonly assumed that the older a player is, the more quickly he’ll get into the NBA swing of things.
           
            To find out if this assumption is correct, I performed a study based on rookie seasons from 1996 to present.  I narrowed the study down to players drafted in the first round and sorted them into six categories: college seniors, juniors, sophomores, freshmen, high school players, and international players.  Each player’s average minutes per game in their rookie season was recorded.  This was a good indicator of how ready coaches felt these players were (other factors come into play, of course).

            Second, I calculated each player’s rookie PER.  PER, or Player Efficiency Rating, was developed by ESPN’s John Hollinger.  According to Hollinger, “Player Efficiency Rating is a rating of a player’s per-minute productivity.”  The league average is set at 15.  More information can be found here: http://www.alleyoop.com/prates.shtm. 

            Lastly, I developed my own system for determining how NBA-ready a player was.  I took each player’s rookie PER and divided it by their career PER and called this percentage the Readiness Rating.  In my study, Readiness Ratings ranged from 34.4 to 135.4 with an average of 87.3 (outliers were removed). 

Older college players had worse rookie seasons than the younger college players.  In fact, each age group played more minutes per game than the groups above it.  Freshmen and sophomores have had the best rookie seasons.  Since 2003, they’ve averaged 27 minutes per game and a PER of 14.64 in their first years.

 High school players played slightly less than the college veterans and foreign players were given the least playing time, averaging just 12.64 minutes per game.  Interestingly, despite getting less playing time, high school players had a higher average PER than both the seniors and juniors. 

According to my Readiness Rating, college seniors were closest to their career levels.  Sophomores were surprisingly NBA-ready (it’s hard to tell why).  As expected, high school players had the most room to grow after their rookie seasons. 

However, before we jump to too many big conclusions, we must consider draft position.  Teams tend to favor taking young players with lottery picks.  Only 5% of seniors were drafted in the top 5 and only 25% were lottery picks.  On the other hand, 29% of freshmen were drafted in the top 5 and 76% in the lottery.  I decided to split up the draft and got these results:

Based on the above tables, it is clear how having less players drafted early has made the seniors’ overall numbers look worse.  However, even if you look at players drafted later in the lottery or later in the first round, older players are still not significantly better. 

            Of the past 12 Rookie of the Year Award Winners, two have been seniors, three were juniors, four were sophomores, zero were freshmen, two came from high school, and one from abroad.

            Based on the above research, there is no evidence that older, college-experienced players perform better in their first year in the NBA than younger players.  Although they tend to peak earlier, they still do not have better rookie seasons. 

Information from thedraftreview.com and basketball-reference.com was used in this study.

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