Even more impressive when you consider the fact that of all the NFL teams Buffalo has the smallest market and Jacksonville the 3rd smallest
http://www.sportsmediawatch.com/nba-market-size-nfl-mlb-nhl-nielsen-ratings/
The last time the Bills went to the playoffs, the economy was booming, the President of the United States had a reputation of misbehaving around women, and Donald Trump was running for President
Wade Phillips was fired 3 times: Denver, Buffalo, Dallas
Wade was also interim coach another 3 times: New Orleans, Atlanta, Houston
Giving him a total of 6 HC dismissals
Given the number of HC vacancies there's going to be competition for the bigger candidates. The Broncos are sticking with the devil they know rather than maybe having to settle for a second or third tier candidate.