It’s customary for coaching staffs to spend a week during the offseason studying each upcoming opponent on the schedule. They watch all of their cut ups, learn personnel and create files on tendencies to ease the cram of game week.
All the coaches who studied 2020 Michigan for the 2021 season basically wasted their time. While some of the personnel remains the same, no program in college football changed so much on both sides of the ball without changing head coaches.
It’s hard to think of a comparable schematic overhaul to the one Jim Harbaugh oversaw at Michigan this season.