I brought this up in another thread that while we may think this is exclusive to our program, I think it's the nature of college football going forward. There is so much money involved with a program, so much reliant on the revenue generated, I can see why they want another set of eyes on the target. Sometimes the hardest deficiencies to see are the ones closest to us.
We always like to point to TO in all things Husker football, but look at Tom in the early years. He had Bob to mentor him to a degree. That other set of eyes. Alvarez was that at Wisconsin as well. Tom tried to be that for BO as well, as I think he felt not being that for Frank hurt. In our current situation you have SE knowing we need to change the dynamics of the program, and he understands he doesn't have the knowledge base to be the sole support for Riley. Insert football expert Devaney. He is the other set of eyes. He can evaluate the staff and talent without the personal relationship issues Riley may struggle with.
I seriously doubt this was a gun to the head, replace him or else move. I'm sure they showed in detail the deficiencies of Banker and the likely upside of making the change. It may have been a little grudgingly, but I'm sure as bright as Riley is, he saw the positives of making the change, though it may have been unpleasant.