1. Grimes was very involved in the game planning, which has as much to do with offensive performance as play calling.
2. Grimes was very important as a CEO of the offense, and in instilling a culture for the offense, which was huge post 2017.
3. He was excellent as a de facto OL coach and recruiter.
4. He is replaceable, but it's possible there could be a drop off in OL development in the long run.