You give up the possibly good bat (but so far, pretty bad bat) for the almost sure thing OBP. Castillo has been very consistent. Plus you open up a spot in RF for Jake Fox, where you hopefully get that power back that you lose from Bradley's potential. If you wait till Aramis is back, I think this could be a nice money saving deal. Bradley's career OBP is .369 while Castillo's is .367. Over the past 3 years, Bradley's is .409 while Castillo's is .362. If Castillo is an almost sure thing OBP guy, so is Bradley.