The Bengals have hired former Buccaneers interim defensive coordinator Mark Duffner as a senior defensive assistant, tweets Albert Breer of TheMMQB.com. 
Duffner, 65, has worked in Cincinnati before, serving as the club’s linebackers coach from 1997-2000 before taking over as defensive coordinator from 2001-02. After coaching LBs in Green Bay, Jacksonville, and Miami in the following years, Duffner joined Tampa Bay as linebackers coach in 2016. He was promoted to interim DC in October after the Bucs fired incumbent Mike Smith. For what it’s worth, Tampa Bay’s defense finished dead last in Football Outsiders’ DVOA but 29th in weighted DVOA, meaning the unit improved as the season progressed.
Duffner will fill two voids on the Bengals’ defensive staff. The first is familiarity, as Duffner worked with both new head coach Zac Taylor and new defensive coordinator Lou Anarumo on the 2014-15 Dolphins staff. Second, Duffner is now the most experienced coach on Cincinnati’s staff, on either side of the ball. Aside from quarterbacks coach Alex Van Pelt, Duffner is the only coach on the team that has been a full-time (non-interim) coordinator.
In addition to hiring Duffner, the Bengals also finalized their roster by hiring four other coaches: Nick Eason (defensive line), Tem Lukabu (linebackers), Brad Kragthorpe (offensive assistant), Jordan Kovacs (defensive quality control).
He was asked to be interim HC when the Bengals fired Bruce Coslet in 2000 but he deferred to Dick LeBeau.
I’m sure nobody else remembers this, but Mark Duffner actually turned down the head coaching job in Cincinnati many many years ago.
When Bruce Coslet quit during the 2000 season, Mark Duffner (the LB coach at the time) was the front office’s first choice for the job. He refused, and deferred to Dick LeBeau.
Nobody but Joe here, who posted it 2 days earlier..