2. Sean McDermott
Sean McDermott joined the Philadelphia Eagles staff in 1999 and held various positions within the organization. He started as a scouting administrative coordinator and later joined Andy Reid's coaching staff in 2001. McDermott initially served as a defensive quality control coach and assistant defensive backs coach.
In 2003, McDermott became the defensive backs coach, replacing Steve Spagnuolo. McDermott's coaching helped both Brian Dawkins and Michael Lewis, the team's safeties, earn their first Pro Bowl berths in 2004. The Eagles reached Super Bowl XXXIX that season but lost to the New England Patriots.
After 12 years with the Eagles, McDermott was fired as the defensive coordinator on January 15, 2011. McDermott rebounded with the Carolina Panthers, becoming their defensive coordinator. The unit ranked among the league's best from 2012-2015 but peaked when the Panthers reached Super Bowl 50. The dominant run was what McDermott needed to get his first head coaching job with the Buffalo Bills.
Since taking over in 2017, McDermott has turned things around in Orchard Park. The Bills are 62-35 under his lead, winning the AFC West for three seasons straight. The team only missed the playoffs once, but McDermott's 4-5 record in the postseason leaves something to be desired. Still, only one season below is better than any of the Bills' previous coaches this century.
As long as Patrick Mahomes and Josh Allen are both on the field, games between the Chiefs and Bills will be exciting. But without a competent coach, all the players on the field amount to nothing. McDermott picked up some useful knowledge from his time with Reid.