I could still see a pen with three lefties. Detwiler and Stammen share duties as the long men. Perez and Blevins both look to be effective enough against righties and lefties, but my guess is Perez would fit more of a traditional LOOGY role and Blevins more of a one inning or two inning guy to get to the back of the pen. Clippard and Storen probably set up Soriano or take his job altogether if he continues to be ineffective other than the "save" stat. This likely means Ohlendorf heads to AAA. I'd rather have Oliver Perez in the pen then Ohlendorf to be honest.
I've been calling for Detwiler to go to the pen for a while. Makes Mattheus redundant. Detwiler can be a lefty specialist or he can be used to get that ground ball.
Honestly I think Taylor Jordan is a better starting pitcher than Detwiler. You put a guy like Detwiler in the pen and we get a ground ball guy, a lefty, and a guy who can throw two innings if need be. The only thing that might change my mind is if Detwiler comes in to ST with great control over all three of his pitches. But, as of right now, 2012 was his ceiling and he is a number 5 starter. He's going to be more effective out of the pen where he can get more velocity on his fastball, making his sinker more effective.