Two years ago, the Buffalo Bills fielded the NFL's fourth-ranked defense. No team in the league had more sacks in 2014 than the Bills' 54. With the arrival of Rex Ryan as head coach last year, that defense was supposed to progress from very good to great.
That defense was going to propel the Bills to the playoffs for the first time in the 21st century.
Of course, that didn't happen. Instead of getting better the defense got worse. Far worse. The Bills dropped to 19th in the NFL in total defense, free-fell to 31st in the NFL in sacks and missed the postseason yet again.