Rex does not have to make a wholesale change to how he goes about coaching. He should look at people who were like him relationship wise and emulate them. Dick Vermeil comes to mind for me. The goal should then be to have a no nonsense GM, OC and DC who Rex can lean on to be disciplinarians...
Time for a new DC and OC next year. Further, promote a GM from within only because I don't think Rex goes. See how two new coordinators and a rookie GM work out... Once you decide Rex is not your guy, then you clean house!!!