Possibly due to the small sample size and number of crappy has beens or never will bes that hang out in AAA. His limited stuff is good enough to get out non-elite hitters, but not to get out the best. Maybe? There are "crappy has beens" in MLB too, not to mention all the AAAA players and defensive specialists. It's not like his numbers in AAA are just okay. Heck, if the walks were down just a bit his WHIP would be under 1. I know people hate Shark, but I'm just saying.