I would argue that it did jack shit for Neifi Perez.
And in 1990 when Ricky Henderson left the Yanks to rejoin the A's and
met Jose Canseco, Henderson went from 6 and 12 HRs his previous 2
seasons to 28 HRs in 1990, with career best 1.016 OPS, won MVP. His
Ruthian .577 SLG that season was nowhere close to any season in the
rest of his career.
You can probably play this game with a lot of players.