I don't mind it when pitchers are lean and sinewy. I've got nothing to back this up but I've always felt the leaner they are, the easier it would be for them to repeat their mechanics. There's less of themselves to get in their way. But then you've got fatasses like Bartolo Colon and Sabathia who pitched well for a long time, I dunno.
Akin probably won't make it as a starter. He's got three average or better pitches but his command has been erratic throughout the minors and I don't see that boding well for him at the big league level. I think he'll have some good starts here and there but be way too inconsistent.
I think his stuff and command is good enough for him to be a valuable multi-inning reliever and I think that's what he ends up as. He could be throwing comfortably in the mid 90's in two or three inning stints and his change and slider are good enough to get both lefties and righties out. Should feel more comfortable going after hitters with the increased velocity, as I've read he likes to a nibble a bit.