From watching Hard Knocks, Gruden seems more old school. I know McVay is a protege, but from a practice perspective, I think Gruden is a little too much of an old school players coach. He is super pumped about scoring in the preseason and winning. His assistants look like a bunch of old School guys too.
McVay runs a fast practice trying to emulate real games as much as possible.
I don't know, just seems like if I had to bet, Gruden is closer Fisher than McVay in terms of where the game is at today.