Aging Sluggers

Interested in the comment by Clay Davenport about sluggers whose finest power seasons came after the age of 35, I decided to take a closer look. By whittling my list of players to only those 36 with 400 or more career homeruns, which included all players through 2003, I found that their peak power season measured by homeruns per at bat came at age 26 and again at 30 (.065 or about 36 homeruns per 550 at bats). However, rather than seeing an increase in power, the curve is almost flat as they simply retain their power longer and don't really start to lose it until past page 37. In terms of NOPS their peak season comes at age 27 (133.1) although once again the decline is very small and they stay well above 100 even through age 41 (108.1).

I also looked at the power numbers for my original sample of 6,000 players and found that their peak power season came at age 27 (.027 or 14.9 homeruns per 550 at bats) and the curve looks almost identical to the NOPS curve I posted previously. I had expected that the peak power season might come a couple years after the peak in NOPS instead of just one year (their peak NOPS was 115.8 at age 26).

Finally, I compared these against the cumulative totals from the eight sluggers mentioned by Davenport (Aaron, Baines, Evans, Fisk, Galarraga, Martinez, Sauer, and Ripken). Here I found that indeed their peak power season came at age 37 (.062) with their peak NOPS at 122.6 at age 35. They also of course reatained their power even longer and didn't show decline until age 41.

I conclude from this that while Davenport is correct that a few sluggers peak late that is not the norm. And while Bonds may in fact belong in that select group, it appears unlikely since even for those sluggers their batting average decreased and their strikeout rate increased even as they were maximizing their power - something alien to the post 35 year old Bonds.