According to the Pro-Football-Reference.com coaching database, there’s only one man in NFL history that has been, at various points in his NFL career, both an offensive coordinator and a defensive coordinator. Can you name him?

There are some coaches, off the top of my head, who have spent time coaching on both sides of the ball. Bill Belichick has been heavily involved with the Patriots offense for about a decade (New England didn’t even have an offensive coordinator in 2009 or 2010), and while he never held any official title, he also was the Detroit Lions receivers coach in 1977. Eric Mangini was an offensive assistant for the Browns and Ravens, and also a tight ends coach for the 49ers, while spending time as a defensive assistant (and later head coach) for the Jets, and defensive backs coach and defensive coordinator for the Patriots (he also was the 49ers DC in 2015, his last coaching gig). Juan Castillo has mostly been an NFL assistant on the offensive side of the ball (never serving as an offensive coordinator, however), but he did get surprisingly tapped as the Eagles defensive coordinator in 2011, and worked in that role for a couple of years (well, he was fired in October 2012).

But being both an offensive coordinator and a defensive coordinator in the NFL? That just doesn’t happen. Our mystery coach was a position coach on both sides of the ball in college, including as offensive line coach at SMU in 1976 and 1977. He left the college game to joint the NFL as a scout with the Bucs in ’78.

Then, in 1982, the Patriots hired SMU head coach Ron Meyer, and Meyer picked our mystery man to became the Patriots offensive line coach. He served under Meyer for his entire tenure in New England, which ended in 1984. In 1985, he joined Darryl Rogers in Detroit as the Lions offensive line coach, and stayed with the team for four seasons.

While our man was in Detroit, Meyer had been hired as the Colts coach, and Meyer inherited defensive coordinator George Hill. But after the ’88 season, Meyer hired our mystery man to join him in Indianapolis as the team’s defensive coordinator. At that point, he had no really experience coaching defense other than at Delaware Valley, Rhode Island, and Idaho State, but Meyer nonetheless chose him for the job. The Colts defense wasn’t great (although it wasn’t terrible, either) in ’89 and ’90, but in ’91, Meyer moved from Indianapolis defensive coordinator to Indianapolis offensive line coach.

Meyer was fired in ’91, so our mystery man next hitched his wagon to… Rich Kotite. He worked as the Eagles offensive line coach from ’92 to ’94, then left with Kotite to become the Jets offensive line coach in ’95 and ’96. It says something about our mystery man’s talent as an offensive line coach that he kept getting these jobs: it says a lot more to realize that he somehow was retained by Bill Parcells in New York after Kotite was fired. In fact, only three coaches from Kotite’s staff were retained, and our mystery man was the only one who had not previously served under Parcells with the Giants.

Our mystery man stayed with the Jets through 2001, serving under two other coaches after Parcells. He had a clause in his contract allowing him to opt out of the Jets contract, in part to enable him to rejoin Parcells if the veteran coach came out of retirement. Our mystery coach is Bill Muir, and Muir joined the Bucs early in 2002 when it appeared that Parcells was going to be the next Tampa Bay head coach. Instead, of course, Jon Gruden became the Bucs head coach, and while Gruden called the plays, Gruden named Muir his offensive coordinator.

Muir stayed in that role as OC and OL coach during Gruden’s entire tenure in Tampa Bay. After Gruden was fired, Muir joined Todd Haley’s staff in Kansas City. Muir worked with Haley with the Jets, and served as the Chiefs offensive line coach in ’09 and ’10 under Haley (in ’09, who served as both HC and HC) and Charlie Weis (in ’10). When Weis left to become the Florida OC, Muir was promoted to offensive coordinator in Kansas City, reprising his dual role as OC/OL coach. The 2011 Chiefs went 7-9, Haley was fired, and Muir retired from coaching after the season.

That makes him the only coach in modern NFL history — and perhaps ever? — to be an offensive coordinator and a defensive coordinator in the NFL.