If you haven't read any of the "ESPN The Magazine Special Report: Who Knew?" yet, go check it out. I'm not quite done with it myself, but there's some really interesting stuff in there. One part in particular reminded me of this post, in the comments of which I used Dave Pinto's Day By Day Database to show the transformation of Bonds' stats starting in the year 2000. It made me think... what about Big Mac? I looked him up and calculated his AB/HR by year (thank you baseball-reference), and sure enough, there is a sort of turning point around '93/94 when he apparently went through some injuries. From '86 to '92 (age 22 to 28), Big Mac hit a homer every 14.2 AB's. From '95 to '01 (age 31 to 37), that figure was down to 8.4.