You don't really believe that the success or failure of a football team (or any team for that matter) relies only on the play-calling and schemes, do you? Who do you think organizes and controls the overall philosophy of the team along with all the practices, meetings, etc? If you think the head coach has nothing to do with the play-calling and schemes then you know little of organization and "chain of command". Oh, and did you think that the offense of Clemson would not skip a beat when Chad Morris left and his title and responsibility was granted to two former players as Co-coordinators? Be honest.