IMO it's got to be Matt Belisle. He was perfectly handled the last three seasons, broken in as a reliever, given the occasional spot start, and got stretched out this year to 177 innings. He doesn't walk a lot of batters though he is a little HR prone, some of that can be attributed to this being his first year as a starter. Really he had the same year as Arroyo, and I think he can improve on the K's, IP and HR's.