Loss to the Jacksonville Jaguars
The loss to the Titans cost the Buffalo Bills the top seed but they could have still had home field advantage against the Kansas City Chiefs. The biggest loss that loomed large, and was arguably one of the worst under Sean McDermott, came in Week 9 against the Jacksonville Jaguars.
The Bills would end up losing 9-6 and was the only time all season they were not able to score a touchdown in a game. When considering the Jaguars were one of the worst teams in the NFL this season, this seems almost inexcusable.
If the Buffalo Bills had won this game, they would have finished with a 12-5 record, the same as the Chiefs, but by winning their matchup in Week 5 would have had the head-to-head tiebreaker. That means their matchup in the AFC Divisional Round would have taken place in Highmark Stadium and with a game this close, homefield advantage could have swayed the outcome in favor of Buffalo.