I don't understand why people still think May should be a starter. He hasn't had much success being a starter. I would be happy if he can become a reliable bullpen arm.
The general worry was 1) he was a decent starter in the minors and probably deserves more rope and 2) his back broke down from pitching more often as a reliever.
Those aren't crazy thoughts. From age 21-24, May was throwing 150+ innings in the minors and he looked like a future workhorse back-end starter. A more durable Scott Baker if everything broke right but someone who might be able to throw 30 stars with a ERA+ in the 100ish range was something you could imagine. He came up in 2014 and was destroyed. He looked horrible in 9 ML starts. The next year, he made 15 starts (80 innings) and in June it really looked like he had turned a corner but for one horrific start. But they moved him to the pen. He was pretty good there and a big part of our near-playoff push.
The next year he was in the pen full time but struggled (as did everyone on the Twins). He struck out a ton of guys but other than that, he wasn't good. He had two long DL trips and was sore several times. Molly ran him into the dirt and he wore down as the season went on. (Another reason Molly should have been fired).
So last year the Twins said he'd get a shot to start and he promptly needed TJ surgery. So now he's 28 years old, on the 60 day DL and not quite sure what role he'll play going forward.