Feel free to believe me or not, but I believe he is more focused on his future career and finding that job than he is with playing football. Can't imagine someone going to school for computer science had plans of going to the NFL (he would have done something much easier than CompSci if that was the case). Game wasn't fun for him anymore, he was more interested in his education and future career, and probably thought at this point he was doing the team a disservice by playing at less than 100% because the game is no longer his focal point.
I wouldn't read into this any further than that. If it (his disinterest) is, in any way, due to coaching problems I would think this is a remnant of the Klenakis era and has nothing to do with Mangino/Blaney.