It’s been said more than once the real mark of a “Most Valuable Player” is the impact said superstar has on his teammates  — hence (some of) the justification for a 1988 NL trophy awarded to LA’s Kirk Gibson despite somewhat less than eye-popping individual stats. Some 3 years ago, Israeli numbers-crunchers Eric Gould and Todd Kaplan attempted to measure the historical impact of admitted PED purveyor Jose Canseco.  As Slate’s Ray Fishman explains, Canseco’s mere presence benefited position players and pitchers alike.

To provide a statistical assessment of Canseco’s alleged influence, Gould and Kaplan compared the performances of every hitter and pitcher who played with Canseco, and analyzed how they changed after exposure to him. Focusing on the power-positions players”catcher, first base, outfield, and designated hitter”who would most benefit from extra heft and bulk, Gould and Kaplan found that contact with Canseco was worth an extra two home runs per year in the seasons that followed.   Canseco’s teammates also saw increases in other power statistics”half a dozen extra runs batted in per season, a one-point boost to slugging percentage, and a handful of additional walks. Meanwhile Canseco did not seem to help teammates in their fielding, base-stealing, and other nonpower areas. (In results not reported in the study, Gould and Kaplan also found that pitchers were able to put in more innings when exposed to Canseco, another indication of The Chemist’s hand in helping his teammates work harder and longer.)

Of course, it’s possible that Canseco’s outsize influence could be benign”maybe he shared with his fellow power hitters a set of batting tips that proved effective. But if this is the case, Canseco’s abilities as a hitting instructor were quite unique”Gould and Kaplan looked at the effect 30 other power hitters of Canseco’s era had on their teammates and found that none of them had a statistically significant influence on the hitting performance of teammates. (Some of these were in fact Canseco’s original disciples, suggesting, perhaps, that not all users become proselytizers.) What’s more, the Canseco effect disappears after 2003, when baseball instituted random drug testing and punishments for those found guilty. If Canseco was merely offering innocent performance-enhancing advice, it stopped working with the advent of drug testing.