I'll say it (although I'm sure some people are going to freak out about it).
Tanner Mangum's problems are upstairs.
As we all can see, he is not at all the same person he was two years ago when he threw for over 3000 yards (i.e., it isn't just the two hail Marys; we remember him as being a competent quarterback who could throw for yardage. I remember being excited that we finally had a quarterback who could throw downfield again).
He can't now. He looks stiff and lacking confidence. His formerly accurate throws are way off. It looks mental to me, because it looks like he is afraid to fumble, get sacked, or throw an interception. I think the Utah bowl game 1st quarter and the Michigan game left scars on his psyche, and in the back of his mind, he is determined not to make big mistakes, so he aims, gets rid of it fast, and doesn't let receivers get open or get separation.
I don't think it's our O-line, or our receivers. I don't think Squally Canada can run his way out of a paper bag, and Trey Dye gets nowhere running up the middle, but Fonua and Tolutau are just fine as runners.
I think it would have been much better for him to wait until after his career before becoming the poster boy for anxiety/depression (interviews, stories, etc.). To have that be the off-season, and then to play so dismally and poorly mentally makes me wonder if he has what it takes from a sports psychology standpoint.