Pete was not short on smarts and play design, but didn't seem to be an alpha that the players would study and play hard for. Payton backed him up, so he got by without being a strong personality.
Really, a team needs a HC that's the heart of both the offense and defense to prevent poaching of their assistants. No one was going to poach a DA or PC, so we kept them for years, many of which were very successful. The HC needs assistants that are loyal and 100% sold on his coaching philosophy.