The following is a reply to a piece from Daryl Morey from the Economist
Jeremy Lin was one of the biggest and most surprising stories of the year. Many sports blogs were quite happy with his performance including HoopAnalyst and ourselves. The reason of course was obvious. While much of the world was saying “Who could have seen Lin coming?” a few blogs were able to raise their hands, point at their archives and proudly say “Right here!” (Arturo’s hand has been up for two years now.) By using advanced stats and scanning data freely available on the net, some bloggers managed to do the work better than some NBA front offices.
Of course there was another side of the story. Daryl Morey, who incidentally puts on a conference promoting advanced stats in sports, decided to come out swinging against advanced stats. It is certainly understandable. When the Knicks make a free agent move that makes you look silly, it’s easy to be upset. Jeremy Lin was signed by the Houston Rockets and didn’t even suit up before being picked up by the New York Knicks two weeks laters. The Knicks did this, because frankly, they couldn’t afford anyone else. The Knicks brilliant move to play Lin was also out of necessity, because all of their other guards were injured or playing terribly. After it all happened though, the big question was: why the brilliant front offices in the NBA couldn’t have seen it coming? Here is Morey’s response:
Defenders of the statistical approach will insist that there was ample quantitative evidence of Mr Lin’s potential. As Mr Weiland noted, he was a dominant guard at Harvard. The models used by teams and amateur analysts alike to predict how college players will fare as professionals invariably identified him as a strong NBA player.
However, those models suffer from an inescapable selection bias: they are based only on the roughly 2% of college players who went on to play in the NBA. As a result, they are all but useless when applied to the broader pool of all college players. In the 2010 draft alone, there were more than 20 other players who had faced relatively weak competition whose statistical probability of NBA success was similar to Mr Lin’s.
This is a surprising reply from Morey. He is in essence saying that the models that notice what attributes track favorably from college to the pros are useless because there are so few pros! The truth from the data is that NBA teams do rely heavily on stats when drafting players, they are just the wrong stats! In Weiland’s analysis we’ll notice he included rebounding and shooting efficiency, which are two stats largely ignored by traditional draft pickers and two important stats when it comes to future success. Morey’s follow up is even worse!
Of course not, counter advocates of the traditionalist camp. Mr Lin and Mr Slater might look the same in a spreadsheet, but they couldn’t look more different on the court. All one had to do, they claim, was watch Mr Lin play—and shame on those teams like the Golden State Warriors, Dallas Mavericks and my own Houston Rockets, who had him in their organisation and failed to recognise his brilliance.
Morey first makes the claim that stats just can’t be used to pick out prospects. In the article he even brings up another example. Josh Slater was a college guard that had similar stats to Lin’s. Slater was not drafted and is not on any NBA team and is nowhere to be found on the Draft Express board. Morey’s use of this knowledge is not to say that he’s snapped up Slater to a super cheap 10 day contract or assigned him to a D-League team. No! His response is to say that any NBA team that employed the eye test would see a difference. In fact, it was a failure of the eye test that NBA teams should be ashamed of when it comes to Lin. After all, spreadsheets are useless when it comes to college draft picks, right?
There is one last point that Morey makes, that is slightly bizarre. He compares NBA teams to elephant mothers:
Neither argument is completely wrong. Maybe Mr Slater could succeed in the NBA, and maybe Mr Lin should have been given playing time sooner. But the structure of professional basketball makes it impossible for teams to give a chance to every prospect who shows some potential.
In contrast, NBA teams cannot hold the rights to anyone beyond the 15 players on their active roster. That makes them more like elephant mothers, who give birth to very few babies and have to gestate them for almost two years.
Morey’s basic point is that teams only have 15 active slots. Every good looking prospect can’t be given an opportunity! The comparison is that teams get two years on their rookie deals and they need to gestate their rookies (really really weird metaphor). There’s a bit of truth in Morey’s statement but I want to take it the other way. At any given time their are only 450 active NBA roster slots. In a given season less than 550 players will suit up. This means teams should not waste their roster slots. And yet, we see teams — like Houston no less — waste playing time and roster slots on players that have never shown signs of being good. This includes players like Aaron Brooks, Jonny Flynn and Earl Boykins. The argument that roster spots are rare and thus teams can’t waste spots on prospects does not justify why they can waste them on players that have had years to prove themselves and haven’t.
What’s more, in the realm of contracts rookie deals are fantastic. A player selected in the NBA draft only has two years of guaranteed money. For the price the Rockets paid to buy out Derek Fisher they could easily buy out the remaining contracts of two first round picks. What’s more, these players are fairly easy to trade. Young prospects are inexpensive, low risk and as we’ve seen from Lin, potentially game changing. Morey’s insistence that a team couldn’t possibly try out every prospect is true. The idea that a team couldn’t easily try it with a few is laughable. And to say that NBA teams don’t have the tools to pick a few good looking prospects is just insulting. Morey has really pointed out that NBA teams have trouble letting go.
I am utterly baffled by Morey’s words. I want to take it two ways. It’s possible that Morey is intentionally playing the fool. The Rockets have made some savvy moves as of late. If Moneyball taught us anything it’s that giving away the formula is not a good recipe for success. Morey may be discrediting useful data in the hopes that other GMs will listen.
On the other hand, if Morey is being serious then he is in essence saying he can’t do his job. If the stats don’t translate to the pros (which is untrue) and teams can’t rotate in new players intelligently (which they can) then what purpose does Morey serve? My take is that Morey is trying to explain to someone how he could mess up and trying to make sure others keep messing up in the same way. At least that’s my hope, because the alternative is also something that comes out of an elephant.