1. Philly special on the 2
2. Blown assignment by Mullings on philly special on the 2
3. 2 pick-sixes
4. Fumble on goal line
The defense gave up 37 points, held Duggan to 225 yards passing at 50% completion percentage and (as you mentioned) forced 3 turnovers. Sure, they gave up 5 TDs but they also did enough to win if the offense hadn't spotted TCU 14 points.
The offense left, at minimum, 6 points on the field. It would be fair to say 10 if you take the field goal on the first drive and don't fumble after the egregious replay overturn of Roman's TD.
If any 1 of those things don't happen Michigan wins that game. If 2 don't happen they win it easily. If none of them happen they win by 3+ scores. Literally everyone who watched that game with the exception of TCU, MSU and OSU fans know that Michigan gave away a game they should've won. Don't @ me with your moronic takes anymore.