Bullet,
I think you're missing Arfin's point.
Steroids don't make someone a "better" hitter, they make the individual a stronger hitter, able to power the ball farther and turn flyouts into homers.
A better way of looking at it, I think, would be their batting averages, number of hits, on base percentage, strikeouts etc., during those years as compared to earlier in their careers. Those statistics give a much better indication of the inherent abilities of a hitter.