The mini-trend this year seems to be teams shifting relievers to the rotation in recognition of the fact that a 180-inning league average starter provides far more value than even a high-end reliever. Daniel Bard, Chris Sale and Neftali Feliz have all made the switch to the rotation this year, and early returns are positive.
With those experiments in mind, here are six other relievers around baseball who I think could help their clubs more by assuming starting roles:
Aroldis Chapman, LHP, Cincinnati Reds
It's great that Chapman has punched out 15 of 27 batters faced this season, but he was a lifelong starter in Cuba and has the off-speed pitches to handle starting in the U.S. if he was just given the chance. His fastball might only sit at 93-94 mph as a starter, but it would likely cause less stress on his arm if he's not airing it out on every pitch, and he has the slider to miss plenty of bats. Arms like this are often forced to the bullpen by injury or lack of command, but Chapman hasn't been hurt (beyond shoulder soreness in November that disappeared with rest) and has never been given the opportunity to refine his command in longer outings. The Reds owe it to themselves to try him as a starter.