Defensive Coordinator: James Bettcher
I was tempted to just say pair Callahan up with a former DC who had just been fired like Ron Rivera, Ejiro Evero, or Brandon Staley. That is still a great option, but I think there is a more realistic option for the Tennessee Titans.
James Bettcher had two stints at DC, the first was with the Arizona Cardinals and the second was with the New York Giants. Currently, he is the linebackers coach with the Cincinnati Bengals and it seems like he will be the next DC in Cincinnati if Lou Anarumo is ever hired as a head coach somewhere.
Paul Dehner Jr. who covers the Cincinnati Bengals for The Athletic said this about Bettcher before the season,
"Defensive coordinator Lou Anarumo came within a whisker of landing the Arizona job and he’ll be on a shortlist again. Linebackers coach James Bettcher would be a likely replacement if Anarumo left — he has coordinator experience and provides a smooth schematic transition."
That familiarity between Callahan and Bettcher could be important, and what helps bolster his case is that he has another tie to the Tennessee Titans. Bettcher was a Senior Defensive Assistant for the San Francisco 49ers in 2021, which means that he would overlap with Ran Carthon's time in San Francisco.
Considering that he has the experience of being a defensive coordinator twice and that he is well thought of enough to be in line for a promotion in Cincinnati, along with his connections to the Callahan and Carthon, makes him a great sleeper target for the Tennessee Titans.