I wanted Archer in the pen last year and I guess my thoughts are the same with Maeda. The Twins didn't have the depth (and I hope that was the only reason) to move Archer, but they do with Maeda. Not a slight on him, it just seems like he'd be the starter best suited for it, and with his age and long layoff due to injury, most benefited by it. Plus, he's already done it.
With how much I distrust relievers, particularly ones coming from other clubs, I think IF the bullpen needs to be beefed up, the best option is a current starter.