This June bullpen experience can only help him refine his craft IMO.
He can dominate minor league hitters with only a FB. He can't do that up here.
There's more pressure for him to use secondary pitches up here, and he seems to be doing it.. Could he use them more? Probably.. But it was really sweet when he started one of those Pirate batters off with a breaking ball and the hitter totally froze with the bat on his shoulder because he was so surprised. The confidence in his secondary pitches will come faster up here, IMO.