Facts don't matter if they don't support Olerud's original incorrect premise.
I think you make a good point. Of course extra base hits are one of the biggest factors in winning, but all teams can do that at this point.
Teams are similarly talented in the playoffs and games are closer because of it. Things like advancing runners, taking extra bases, making defensive plays, etc. are magnified to some extent.
There isn't a stat for it, but anyone who has watched playoff baseball knows that the formula is a little different in the playoffs.