Ok - so mostly the fear of the unknown. I suppose that's reasonable. So does that mean it's preferable that he leaves CU to get some OC experience before we'd want him back in that capacity? I'm not sure I'm there. Perhaps he just needs more years of experience before he would be a viable candidate as sole OC.
I can't imagine he'd feel great with a demotion which may force him to want to move on. Hope not.
It would depend on how badly Chev wants to be a play caller. Lot of other titles and responsibilities he can be given that don't involve him becoming the OC.