This is the question Cy Morong attempts to answer on his blog Cybermetrics—what a good blog name. Cy uses a sample of pitchers who pitched a minimum of 500 innings in the five years before before their fortieth birthdays and 200 innings in the following five years. He uses ratios of pre- and post-40 performances to evaluate the change in several statistics.
In general, Clemens does much better at the older age. But he is not always first or close to first in the rankings of the various stats.
Jonah Keri makes a brief comparison between Clemens and six other pitchers using ERA+.
Even among the greats, Clemens stands out. He appeared to be declining in his thirties, but put up a monster season at age 34, posting a 221 ERA+. It’s not uncommon, though, for power pitchers to take big steps well into their thirties—the real divergence came later. After two decent seasons at ages 39 and 40, Clemens won a Cy Young Award in 2004 and posted an outrageous 1.87 ERA in 2005, for a 226 ERA+ that’s the thirteenth-best of all time. The huge spike at such an age was unprecedented in major-league history.
For some reason he calls out my analysis in a rather bizarre way.
Nor is he cleared by research from the blog Sabernomics, which found little evidence of jumps in performance after the injections McNamee alleges. The problem with this analysis is there’s little information on the effects of PEDs on pitchers. They can increase muscle mass and thus fastball speed; some also believe they speed injury recoveries and allow one to work out more often, increasing durability. Clemens could have taken PEDs preemptively—preventing falloffs rather than triggering spikes—or taken doses too small to have an effect. And, of course, he could’ve taken PEDs on other occasions.
To this, I say, “huh?” First, I didn’t look at spikes in performance after use to find evidence of use. I looked declines in his performance prior to use at specific times alleged by Brian McNamee. The idea was that Clemens would be more tempted to use at times he appeared to pitch poorly. I found that these were odd times to use. Second, I also noted a general aging trend in his performance. I noted the same post-40 spike that Keri finds, but I interpret it quite differently. What I find interesting about this spike is that it occurred during a time when Clemens still trained with McNamee, yet McNamee was not aware of any steroid use at the time and MLB was conducting steroid testing. While it is possible that Clemens would get his steroids from another source, I find it odd that Clemens would go to others for steroids when McNamee had already allegedly helped him use them.
Update: I corrected my initial misspelling of Jonah Keri’s name.