I'm telling you, that type of arm bar grappling is pretty common amongst big guys in basketball. Watch Andrew Bogut, watch Marc Gasol, watch Noah or Pau. It looks like Love put his hand in Olynyk's stomach, you can see Olynyk grimace, and then Olynyk clenches and pulls the arm.
Like I said, I've had almost the exact play happen to me during a game. Chasing a ball towards the sideline, put my arm out to shield a guy and because he pulled my arm to gain leverage at the same time that I was pulling away, I dislocated my shoulder. It's just one of those things, but yeah it's too bad.