His NFL problems:
You can’t run a QB in the NFL like you can in college. They’re too valueable so instead of adjusting his offense, he’d run option concepts where the QB never kept the ball.
You can’t play at the same tempo in the NFL. They refs will stand on the ball to some extent.
Because you can’t run at an insane tempo in the NFL, it’s easier for a defense to not get caught and his plays started to get scouted.