Just guessing, but I doubt it was showing up to class late. That would be handled in other ways unless it is habitual. My guess would be a poor verbal decision, cheating or something worse.
There was a post somewhere where he reportedly "went off" on an academic advisor and maybe told a freshman OL to tell the coaches he wasn't going to practice and that he would play anyway.
NONE OF THAT IS VERIFIED AND IT IS ALL RUMOR but that was one snippet posted by 1 poster who may or most likely may NOT have direct knowledge of the event or events.