Chen is the only Oriole at 160. Nobody else is even close.
The only thing worse than having to worry about tiring young arms is having a number of unknown quantities, and the Orioles, by virtue of having to play musical chairs with their rotation all season (masterfully, I might add) is the lack of confidence in what to expect going down the stretch.
That being said:
Chen, first year in MLB.
The aforementioned Tillman.
Tommy Hunter 121 innings in the bigs, 29 innings in the minors (150)
Jason Hammel 109 innings in the bigs, coming off the DL, though he has averaged 174 over the last 3 seasons, so that's a plus.
Jake Arrieta 101 in the bigs, 56 in the minros (157)
Brian Matusz 89 in the bigs, 47 in the minors (136)
Hey, beat the Yankees and everyone's happy. And truthfully if the O's are the team that beats out the Angels for the second WC, that would be the best worst case scenario for me, even if I have to hear about it on this board for all of eternity. But I'm still not betting on the O's. Or the A's, because history and the stats tell me not to.