Why not wait until the situation necessitates it though? Even when you're trying to win, you can't just fly off the handle and abandon all reason. We know, objectively, that Castro is very unlikely to be more than a few runs better than Guilmet/Lopez/Delabar/West this year, if he's better at all. Why not try to get through the season without using him, given the low potential reward? If at midseason he's tearing through NH and you need a pen arm, sure, give him a call. But choosing him now, with an 8-man pen, when you've cut a bunch of other arms that are probably as good in 2015, seems silly.