RE: Fisher simply didn't adapt to the game.

Fisher was not a smart guy. He wasn't an innovator. Did you ever see any effective halftime adjustments?
All Fisher ever did was to do things the one way he how to do it; and as the NFL game evolved he seemed to have little ability to evolve along with it.

The game outgrew him. It would be like bringing in a guy to run Apple that doesn't like technology.