Relievers are a dime a dozen. Bailey had 1 good year at age 25 then the K Rate declined big time. There was a reason Beane let him go, he knew time was running out to get max value.
Reddick in the minors was a player who generated extra base hits 40 plus percent of the time he reached base, which the Scouts will tell you translates to gap power at any level, more times than not. Bust trade then and it would be a bust trade now to deal JBJ for anything less for a Verlander type arm or a JDMartinez type hitter.
See CSmith. This is why its critical to develop your own Relievers in the ML System. It's to much of a risk to trade any prospect of value for a relief pitcher. So far Kimbrel has been the real deal but as we see the HR's allowed are starting to climb this season.