Yesterday, in response to a post by John evaluating the case that Roger Clemens used steroids, I noted Clemens’ remarkable pitching statistics during 2004-2006, when he was age 41-43. During that time, he posted an earned run average (ERA) of 2.40, far better than his career ERA of 3.12.

However, reader Vincent Freeh points to a fact that, inexcusably, I overlooked. In 2004, Clemens came to the National League and pitched there through 2006. The National League doesn’t have the designated hitter, and thus fewer runs are scored there. According to Freeh, normalizing the ERA by league would close the gap between Clemens’ career ERA and his ERA from age 41-43 by 0.2 to 0.4. At that point, the improvement in his statistics does start to resemble Warren Spahn’s, the example John invoked as precedent for what Clemens has accomplished in his 40s. As Freeh says, the adjustment “doesn't prove [my] point false, but makes it less [powerful].” I still believe that, for example, the ERA of 1.87 that Clemens posted at age 42 in 2005 (when the league ERA was 4.23) provides good cause for suspicion. But suspicion, of course, is not proof.

Freeh, by the way, is a computer science professor and the co-founder of GridIronMine.com, which provides scientific analysis of (American) football.

Posted by Paul at 8:38 PM  |    |