Whiplash Plot Holes?

I've read in articles that Whiplash has several plot holes, but none elaborate. Can someone do so here? Perhaps I was too taken by the performances and finale, but I loved the hell out of this film.

The only implausibility I see in the end is that it seems a bit insane that Simmons' character would sabotage himself AND the band he was conducting just to get back at Teller's character. But still, a part of me thinks he's psychotic enough to do it.