2. Dennis Allen, former New Orleans Saints head coach
Allen was fired by the Saints after a 2-0 start this season became 2-7 record, and with a 26-53 record over parts of six seasons his days as a head coach are surely done. Overall, his fitness to be a head coach was easy to question at both stops he has had (the Saints and the Oakland Raiders).
What can't be questioned is Allen's acumen as a defensive mind. As noted by Al Karsten of Pride of Detroit, the Saints' defense improved dramatically over his tenure as the Saints' defensive coordinator (2015-2021) before he replaced Sean Payton as head coach. During Allen's two full seasons as the head coach (2022 and 2023), New Orleans had a top-10 scoring defense.
Dan Campbell and Aaron Glenn spent five season (2016-2020) with Dennis Allen as the Defensive Coordinator for the Saints.
— Al Karsten (@FootballGuy_Al) November 4, 2024
His defenses improved from 31st in Points Allowed and 27th in Yards Allowed to 4th and 5th in 2020.
Not a good HC but could help Lions in a Defensive role. https://t.co/MUVit5hgDd
Allen's tie to Campbell from their years together as assistants under Payton in New Orleans could be meaningful if Glenn has to be replaced.
1. Kelvin Sheppard, Lions linebackers coach
Sheppard is a rising star on the Lions' coaching staff, with the makings of being a future head coach as he also works with a continually injury-thinned group. But he would likely have to become a defensive coordinator before that opportunity comes, and in that sense it's possible Glenn (or offensive coordinator Ben Johnson, if he takes a head coaching job) will want to take Sheppard with them elsewhere.
But until shown otherwise, Sheppard stands as the most likely next Lions' defensive coordinator whenever Glenn takes a head coaching job. You can bet Campbell will make every effort to keep his linebackers coach around as defensive coordinator if Glenn leaves, with most any other available option falling behind Sheppard in the pecking order.