Frank Stephenson of Division of Labour sent me a link to this the other day, but I haven’t had time to read it because I’ve been working on the The Hardball Times Annual (have you reserved your copy yet?). And now that Tyler at Marginal Revolution has posted a link to it this morning, I need to get on the ball and get this out there.
“Has Home Run Hitting Changed in Major League Baseball” is a paper by UC-Irvine economics professor Art De Vany who runs a fantastic blog that I was previously unaware of. Here is a summary of his conclusion:
There is a lot of speculation about steroid use in MLB, but the evidence is mostly anecdotal, misleading and incomplete. It is surely not an adequate basis for public policy to 1. assume that there is an increase in home runs, and 2. to assume that steroids are the explanation. The first statement is incorrect, there has been no increase. That makes point two vacuous. There is no need to invoke an external explanation like steroid use when there is no change to be explained.
The same law of home runs holds now that held 40 years ago. Year to year differences in home runs require no explanation; they are all within the variation of the outcomes under the stable probability distribution of home runs. The burst of new records does not require an external explanation like steroids; they are part of the pattern that comes from the nature of the law of home runs.
The pace of new records in recent years is due to the extraordinary accomplishments of three prodigious hitters. We have lucky enough to see three Babe Ruth’s in this generation. Hitters such as these may never appear again. You cannot take an ordinary player and turn them into home run hitters of the accomplishment of Bonds, McGwire, and Sosa by dosing them with steroids. It may even be harmful. Home run hitting of that magnitude is human accomplishment at its highest, as incomparably rare as the work of Einstein or Wagner.
Even greater performances are possible because the long upper tail of the law of home runs gives them positive and non-vanishing probability. The law of home runs says that the probability that Babe Ruth’s record of 60 home runs would be broken is 0.0109, about one in a hundred. Given enough time and hitters, it was almost sure to fall. Barry Bonds’ record of 73 will be harder to break. The probability that his record will be broken is 0.007206, about seven in a thousand.
This might be the most important sabermetric paper written this year. Certainly, it has the biggest policy implications. Please, read it. I’ll be doing so shortly. The media needs to be aware of it.
Addendum: I had a few minutes to read through the paper, and I think it’s quite interesting. However, I’m going to have to think about it some more. I think he’s right, and it’s a very good paper. His idea is so simple, that I can’t believe no ones thought of it before. It seems that the best ideas are often like this. Great performances are rare and very unpredictable. We just happened to witness some of them very recently, that’s all. And what up-tick in home runs among all players that we do observe is explained by other factors.