This is a remarkable story which I touched on here.
Bisons manager Tim Tuefel explains how Schwinden is doing it:
“This year he seems like he’s coming in with more weapons. He has a curveball now he’s working with, and a changeup. Plus, he’s got that regular fastball and a cut fastball. He almost uses that as a slider. He still needs to mix in his changeup a little bit more, and he showed me a decent curveball. If he can mix all of those pitches up, he’s been very effective up here so far doing that and keeping the hitters off-balance.”