>But in doing the latter, isn't he doing the former?

No. He's observing that park effects shouldn't be a stick with which to whap players on unfashionable teams.

Walker also compiled 73.2 fWAR. While Posnanski was excluding poorly-applied arguments, he could have added the one where we rarely bother to think of corner outfielders as good defenders. And if he'd use Rice as the counterweight for that one, I'd be just as pleased with his work.