The Buffalo Bills have to be the most cursed franchise in sports. Not even just American football.
The Bills have never, ever been heads up better than their best competition. Now you may be able to argue that in 50/50 games, like this one against the Chiefs, they're a bit behind that mark, but I don't care. In most of their losses, they were clearly the inferior team. Against the Giants in a 50/50 Super Bowl, and they lost by one. Sounds about right. They're not exactly cursed but were damned lucky to be in the AFC East. The Patriots were the successors to the Bills and had slightly better results thanks to Brady and Bellicheat.
The common denominator in both of these scenarios and in the case of the 1990's Bills, one, massively overlooked reason why they were so unprepared, out-matched physically band mentally, beaten so handily was due to bad coaching, lack of execution, and focus. Levy's a HOF HC, but like Bud Grant and Dan Reeves before him, he couldn't elevate his abilities and skill sets and those of his players in the biggest game of the season. Most times, like 95% in crucial, big-time circumstances, they'd probably find a way to win, that OTHER 5% is when they can't win THE SUPER BOWL, ever.
And like with Levy in the late 80's and 1990's, one of the major reasons why Buffalo can't seem to advance to the Super Bowl is due to bad coaching and lack of decisive decision-making in Divisional Round, AFCCG'S. Good NFL HC's are like good NFL Pro Bowl QB's, like Danny White, they can get you to the playoffs but they don't elevate their game to a higher, transcendent level in big games like great QB's and HC's can like Tom Brady, Drew Brees, Patrick Mahomes, Belichick and Andy Reid.
Sean McDermott is a very good HC, but usually their not the ones who typically win Super Bowls, and if by some chance, they get lucky like a Zac Taylor, they don't end up winning the game.