Pivoting off a recent fanpost about another Phillie in historical context: Does Ryan Howard have the biggest single-season platoon split of all time? I don't know how to check this, but it's at least plausible:
vs RHP: .313/.388/.679
vs LHP: .197/.289/.352
That's a difference of 426 points (!) of OPS, roughly the gap between the best hitters in the league and the worst. Off the top of my head, I can't recall another player quite like that. Anyone?