You have to factor in who he hit those dingers against. If he's playing teams that are NOT in a pennant race, he's probably facing AAAA pitching.
I would think the grind of playing would take precedent over the intensity of workouts. Of course, the juice helps you recover so you could definitely intensify your workouts while playing. That said, yes, one would pack on more muscle in the off-season because one would have more time.
It's possible that's exactly what you've done.
Probably both. But you were already stupid so it's hard to tell.