Assessing the 2014-15 Rookie Class

The 2014-15 rookie class was being touted as possibly being one of the best in history even before the 2013-14 season began – the savior class after the fiasco that was the 2013-14 rookie class. With players such as Andrew Wiggins, Jabari Parker, and Marcus Smart, this was supposed to be the class that could potentially challenge the LeBron, Melo, D. Wade, Bosh class of 2003-04 for the title of best draft class in recent history.

With one trimester of the season in the books, we’re closer to the infamous 2000-01 rookie class than the golden 2003-04 class. When looking at individual performances – Wiggins may be the next James Posey based on his performance thus far, Jabari Parker is out for the season with a torn ACL, Embiid is essentially out for the year with a leg injury, and Elfrid Payton, Bill Simmons’ pick for ROY, is on pace to have one of the 20 worst single-season free-throw percentages for a guard in NBA history.

 I wanted to quantify how the class as a whole compares not only to 2013, but to other classes before it. There are tons of ways to do this – for example, Kevin Pelton at ESPN uses his WARP metric (essentially a wins above replacement metric) to determine that the 2000 class was the worst in recent history, followed by 2013 – which certainly passes the eye test. I do not have the data to replicate this, however.

The method which I used was to look at the percentage of available minutes in the NBA season as of the end of the first trimester that were played by rookies. My reasoning for using percentage of minutes used relative to available minutes is this – if you are on a team, and you play more minutes than anyone else on the team, it means that the coach trusts you more than any other player to put the team in a position to win (or that you are the coaches son, but most likely the former). It may sound oversimplistic – especially in today’s world of crazy metrics, but it definitely passes logic. A player who plays a minimal number of minutes per game might have great per 36/48/possession statistics, but there is a reason that player is only given a minimal amount of minutes – the coach does not feel he can help as much as other players towards the goal of getting a win in an NBA game. Even if not on a strong team roster-wise, a coach will play the guys each game that gives him the best chance to win (even if that team is the 76ers).

I went back as far as the 2005-06 rookie class, but not any further because 2005-06 was the first year that teams could send rookies (and sophomores) down to the NBA Development League.  (if you look at the stats prior to the 2005-06 season, the percentages for this playing time metric are about 15% higher on average than post 2004-05 because rookies that likely would be sent down to the NBADL had they been drafted post 2004 were instead on NBA rosters, and thus likely got some garbage minutes in games throughout the season).

For each NBA season from 2005-06 through the current 2014-15 season, I used the nba.com/stats portal and scraped player data for the first 30% of the NBA season (roughly around Christmas +/- a few days depending on the season, 2/4/2012 for the lockout year in 2011-12) in order to standardize my results (since I would assume this percentage increases as the season progresses, especially as teams that are eliminated from the playoffs begin to expand playing time for end of bench players who they want to develop). The results show that the 2013-14 and 2014-15 rookie classes are the third and fourth worst out of ten seasons – which is bad, but there were worse (2007 and 2010).

So what does this mean as far as projecting the future abilities of this draft class? I mapped the total win shares (essentially the number of wins a player was responsible for) that each rookie class generated over its first three seasons (here is the query) against the data in the graph above (for each year that we can map out three seasons worth of win shares – so through the 2011-12 season). Although there are only a few samples, it shows that there is a somewhat significant correlation between the two metrics –

With an R-Squred value of 0.53, we can thus we can somewhat reasonably predict that the 2013-14 and 2014-15 rookie classes likely will not be as strong as say 2008-09 (Derrick Rose, Kevin Love, Russell Westbrook), which produced more win shares than the 2003-04 class (379 to 341), or the 2011-12 rookie class (Kyrie Irving, Kemba Walker, Nik Vucevic).

One additional thought based off this was to look at each two year period and see how 2013-14 and 2014-15 compared to other two year periods. This could perhaps make a case that the 76ers picked the wrong time to trade for numerous draft picks. It’s interesting because the 2006-07 and 2007-08 seasons on average had a smaller percentage of available minutes played by rookies than the 2013-14 and 2014-15 set (by a small margin), but the Sonics/Thunder drafted Kevin Durant in 2006-07. While it may not have been the best two year period to draft as many players as the 76ers did, it’s really hard to use numbers here to say whether or not the 76ers picked the wrong time to tank. Certainly the odds are stacked against this class as a whole, but there could certainly be outliers – and the key for the 76ers is to find those outliers through good scouting.

My next question was to try and understand why this year’s crop is playing a relatively low number of minutes. For this I turned to the effective field goal percentage (eFG%) metric – the most important of Dean Oliver’s four factors. The past two years represent horrible years relative to the eight prior to it in this metric

From this I can deduce at least to some extent that the drop in available minutes played by rookies the past two seasons could be that these players simply are not as skilled shooters and coaches recognize this.

It could also be that coaches are scared to play rookies. It’s no secret in the NBA that the job security of coaches are tenuous at best, and the small playing time could be tied to that as well. Only one current NBA head coach (Gregg Popovich) was hired prior to 2008 and eighteen coaching jobs have turned over since the 2012-13 season. With the exception of the few teams each year that do not have the roster in place to win more than 30 games, coaches are expected not stall in the quest to win games – which perhaps is now starting to come at the expense of developing rookies. 


Data courtesy of basketball-reference.com