Why should a guy be penalized if he is blocked and forced to play corner outfield because the team has an established CF? If you have a CF quality defender playing in a corner, he is going to have more range, and won't be penalized, because he is making more plays than the peers at his position. Going further, shortstop is more difficult to play than center, but is it really that much more difficult than third? Pujols started off his career at 3B, imagine how much better his offensive numbers would have compared against shortstops. I think there's a certain level of defense that teams will tolerate. It might have been worth it for the Brewers to try Gamel at SS in the minors this year, so he could have replaced Yuni at some point. He may be a -25 or -30 defender, but if managed to put up an .800 OPS, it would have been a decent tradeoff, maybe even a good one. But teams don't seem to try to do that. Look at catchers. Catchers offense is just terrible for the most part. If you were Brendan Katin and you put up a .845 OPS in the minors over your career, wouldn't it be worth a try to learn how to play catcher in the offseason? But catcher defense is really, really important, so teams don't try to do stuff like that.