5 candidates to replace Aaron Glenn as Lions defensive coordinator

4. Mike Zimmer

Zimmer was let go after eight seasons as Minnesota Vikings head coach, and it’s possible he takes a year off to recharge or it’s also possible he’s done coaching. But there will be rumors of him landing as a defensive coordinator somewhere until it doesn’t happen, with the Dallas Cowboys the easy spot if defensive coordinator Dan Quinn gets a head coaching job.

But it’s Dallas roots that could land Zimmer in Detroit if the circumstance presents itself. Zimmer was a Cowboys’ assistant from 1994-2006, overlapping with Lions’ head coach Dan Campbell’s time as a player there (2003-2005). The two share what we can call “Bill Parcells roots”, and if Zimmer is going to coach somewhere in 2022 joining someone he sees as like-minded feels like a nice fit.

3. Mike Macdonald

Macdonald just completed his first season as defensive coordinator at the University of Michigan, as Jim Harbaugh re-shaped his coaching staff. But now Harbaugh seems to be eyeing an exit back to the NFL, and it’s fair to assume a new coach (Matt Rhule?) won’t retain the entire coaching staff.

Macdonald has coached in the NFL, climbing from intern (2014) to linebackers coach (2018-2020) over his time with the Baltimore Ravens under John Harbaugh. The next step on the ladder for him would seem to be NFL defensive coordinator. If the Lions lose Glenn, almost independent of if Jim Harbaugh leaves Ann Arbor, there could be an opportunity for him.