Reference Points for Evaluating College Performance

The 2008 NBA draft has been the subject of a few posts in this forum.  Two of these were penned by Erich Doerr before the draft:

The 2008 NBA Draft Preview

2008 Win Scores NBA Draft Preview

In addition, I wrote the following soon after the draft:

Falling in Love with Potential on Draft Night (and Erich also offered the following Draft Recap at Draft Express: Win Scores 2008 NBA Draft Recap)

Each of these posts referenced Win Score, the simple metric of player performance discussed in The Wages of Wins.  Today’s post is also going to employ Win Score in looking at the 2008 NBA draft. 

Finding a Reference Point

The difference is that today’s post is going to introduce some important reference points.  Specifically, I have calculated the average college Win Score per 40 minutes [WS40] at each position from 1995 to 2008 (the specific data set considers all players who were drafted in these fourteen seasons, and who played at least 500 minutes their last season in college). 

Here are these averages:

Centers: 12.30

Power Forwards: 12.48

Small Forwards: 9.92

Shooting Guards: 8.43

Point Guards: 7.30

The numbers essentially follow what we see in the NBA.  Big men – because they rebound in greater numbers and tend not to turn the ball over – post higher Win Scores.  Smaller players are the opposite and post lower Win Scores.  Because positions in basketball are complements in production (economic talk for the idea that teams appear to need all positions to produce wins), it makes sense to evaluate a player relative to what we generally see from a player’s position.

Back to the 2008 Draft

To put these numbers in perspective, consider the performances of Mario Chalmers and Roy Hibbert.  Chalmers – a point guard – posted a 10.38 WS40 (Win Score per 40 minutes) last season.  Hibbert’s WS40 was 12.89.   If all you look at is Win Score – and you don’t consider position played – you might conclude that Hibbert did more in college last season.  But because Hibbert is a center, his performance relative to the average at his position was not as impressive as what we saw from Chalmers.  Although both were above average, Chalmers was simply the more impressive.

Table One moves beyond a simple comparison of Chalmers and Hibbert.  Looking at this table – which reports what all players drafted out of college in 2008 did during the 2007-08 college season — we see a story that is quite similar to what was noted in past posts on this last draft.

Table One: Reviewing the 2008 NBA Draft with Win Score

The top players in this draft class – according to the 2007-08 college numbers – were Michael Beasley and Kevin Love.   Derrick Rose – the first player taken in the draft – was actually out performed by fifteen other players taken out of college.

Now what does all this mean?

  1. There is a relationship between numbers in college and the NBA. And in a moment I will explain where that relationship will be discussed.
  2. The consistency between college and professional numbers in the NBA exceeds the level of consistency we see in professional numbers in baseball or football.  In other words, basketball players are more consistent from college to the pros than baseball players are from one season of Major League Baseball to the next.
  3. All that being said, these numbers are not a guarantee.  It’s perfectly possible for a below average performer in college to become an above average performer in the NBA. Likewise, above average college numbers do not guarantee an above average NBA performance.

So what does this tell us about players like O.J. Mayo, Eric Gordon, or Joe Alexander?  Each of these players was well below average last season.  And each was chosen in the lottery.    Does this mean that the Grizzlies (who now have Mayo), the LA Clippers (who drafted Gordon), and the Bucks (who selected Alexander) all made a mistake?

Not necessarily.  Again, it’s possible that a player who was below average in college could perform quite well in the NBA.  But the odds are somewhat against this outcome.   Consequently, one would think that decision-makers on these teams at some point had to consider why these players performed so badly in college.  And furthermore, each team should be able to explain why each player will become transformed once each starts collecting money from the NBA.

Let me emphasize this point.  The ranking of players in Table One is not necessarily what we will see in the NBA.  But we can expect there will be a statistical relationship between what we see in Table One and the final outcomes we will see when these players play in the Association.

One more note on statistical relationships… I do not find a statistical relationship between relative college performance and draft position.  At least, that’s the story in 2008.

And one last note on the draft…our next book has an entire chapter devoted to this subject. Hopefully that chapter will address many of the questions people have about evaluating college performance and predicting the future in the NBA (it will certainly address the link between college and NBA numbers).

Brief Comment on Non-Sports Economics

Before I close this post, as an economist I feel I have some obligation to comment ever so briefly on our recent economic troubles.  Beyond sports I am very interested in economic history (as well as the history of economic thought).  In light of what I know of these subjects (and what I teach), I have two quick comments:

  • It would probably benefit observers – who invoke the Great Depression in talking about recent events — to actually understand the events of the Great Depression.  More specifically, I think people should know that we are a long way from another Great Depression. And if you understood the details of the Great Depression you would see why comparisons between now and then are an immense stretch. 
  • In addition, I am quite irritated by people who discuss the proposed bailout as an example of “creeping socialism.” Such people tend to throw out the “socialism” word whenever people discuss the government playing a role in the economy.  One only needs to read Adam Smith (as well as John Maynard Keynes and many, many recent economists) to see that government does indeed have a role to play in a market economy.  Certainly the extent of the role is a matter of debate.  So it’s possible to disagree with the need for this bailout. But you have to try harder in making your argument than just saying “creeping socialism.”  My sense is that people who evoke such terms couldn’t pass a test on the actual nature of socialism (and therefore, should stop using such language).

Okay, those are my brief thoughts.  As you can see, there are number of non-sports blogs linked to on the right.  For more information, I strong urge people to click on over and see what the following seven blogs have to say on this subject of the current financial crisis and the proposed bail-out:

DeLong’s Semi-Daily Journal

Economix

Freakonomics

Greg Mankiw’s Blog

Marginal Revolution

Matthew Yglesias

Paul Krugman-Conscience of a Liberal

– DJ

The WoW Journal Comments Policy

Our research on the NBA was summarized HERE.

The Technical Notes at wagesofwins.com provides substantially more information on the published research behind Wins Produced and Win Score

Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:

Simple Models of Player Performance

Wins Produced vs. Win Score

What Wins Produced Says and What It Does Not Say

Introducing PAWSmin — and a Defense of Box Score Statistics

Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.

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