No matter what rationalizations are made the basic truth is we need better coordination of this defense. The secondary is not deceptive enough pre-snap, guys are not playing with anticipation in zone, they're not well prepared in man either for route combinations of opponents, and we're not going to find a top edge to bail us out again back there. They need to fix the secondary which means a DC with a strong grasp of what is required.
Staley would meet that objective. He will be available this offseason I think. Fangio obviously would as well. Both are well steeped in the chosen scheme McVay prefers.
It sucks for McVay but to date he has always made that hard call when it had to be made. So I have faith he'll do what must be done.