19 NFL teams have changed head coaches in the last 3 seasons
The Buffalo Bills made it official on Tuesday, firing head coach Rex Ryan just days before the final game of the season.
Ryan is the third coach to lose his job this season. In addition, the Bills are the 19th team to change coaches since the end of the 2013 season.
While a lot of teams have been with their current head coach for fewer than three seasons, there is actually quite a bit of job security in the NFL. Five coaches have been with their current team for at least ten seasons. The NBA, MLB, NHL, and English Premier League have five such coaches combined.