Sean McDermott's relationship with Kansas City Chiefs coach Andy Reid has been well-chronicled over the years. But the Bills coach is close with so many others from his days as an assistant with the Philadelphia Eagles.
On Monday, McDermott spoke glowingly of Steve Spagnuolo, the Chiefs' defensive coordinator, who was one of many individuals on Reid's staff who went on to become head coaches.
The two will be on opposite sidelines Monday night when the Bills visit the Chiefs for an AFC Divisional Round playoff game.
Spagnuolo and McDermott worked together on Reid's staff for eight seasons before Spagnuolo moved on to become defensive coordinator of the New York Giants and eventually head coach of the St. Louis Rams.
The two remain, in McDermott's words, "extremely close. Just just what he taught me, what I learned from him, the amount of time he spent with me when he really didn't need to do that, extremely gracious person — both Steve and his wife as well. Great people."
McDermott admires Spaguolo the way he does Reid.
"I kind of look up to him from a bigger-brother standpoint, although I have a brother myself," McDermott added. "It's just just the way he has helped me over the years, even coming into the head-coaching position. I remember Spags sent me a book that I still have to this day about leadership, so I just can't say enough about him."
But just because Spagnuolo, McDermott and Bills defensive coordinator Leslie Frazier all worked under the late, great Eagles defensive coordinator Jim Johnson at the same time, it doesn't necessarily mean the defenses on each side will be identical.
"I think we've taken our own routes — all the coaches that were under Andy and under Jim, on that defensive side in particular, with Ron Rivera, Leslie Frazier, Spags," McDermott said. "We've all kind of gone off and done our own thing, and yet there's a lot of the core of what Jim had in his system. But then there's some additions that have been made to it and tweaks and whatnot, just to more than anything stay current with the game."
Nevertheless, the chess matches will be fascinating because of how familiar each staff is with the other's methods and because of how often these teams have started playing since the Bills have become an elite franchise.
The teams met in the regular season and again in the playoffs last season for the right to advance to the Super Bowl. The Chiefs won both.
They met again in October, with the Bills getting some revenge in a 38-20 victory.
Now the Chiefs are standing in their way again in what could be a playoff matchup for years to come.