Five Under-the-Radar Lions DC Candidates

The Detroit Lions will have to find a new voice to lead their defense.

With Aaron Glenn off to coach the New York Jets, Dan Campbell will be tasked with finding a new defensive coordinator for the first time in his tenure. While there are several intriguing candidates internally, headlined by linebackers coach Kelvin Sheppard, the Lions could look externally as well.

The Lions have already started the process, interviewing 14-year NFL vet and Michigan native Larry Foote for the position earlier in the week.

Here are five under-the-radar candidates for the Lions to evaluate as potential defensive coordinator candidates heading into the 2025 season.

Jim Leonhard

Current position: Denver Broncos Defensive Pass Game Coordinator/Defensive Backs Coach

Leonhard has ties to Dan Campbell from their days together in New Orleans, and has since done a stint as a defensive coordinator and interim head coach at Wisconsin before coming back to the NFL. He just completed his first season with the Broncos under Sean Payton, where he worked closely with one of the game's best corners in Patrick Surtain.

He spent 10 years in the NFL as a player, carving out a career after beginning his college tenure at Wisconsin as a walk-on. From that standpoint, he fits the Lions' grit mentality and would suffice within the staff's mold of former players.

Leonhard was known for having solid defenses at Wisconsin, and his scheme could certainly translate to the NFL. The experience with longtime coordinator Vance Joseph will only help his case.

MORE: Five Under-the-Radar Lions' OC Candidates

Former Wisconsin Badgers defensive coordinator Jim Leonhard. — Former Wisconsin Badgers defensive coordinator Jim Leonhard against the Oklahoma State Cowboys during the 2022 Guaranteed Rate Bowl at Chase Field. | Mark J. Rebilas-Imagn Images

Mike Zimmer

Current position: Dallas Cowboys Defensive Coordinator

The former head coach of Detroit's rival Minnesota Vikings, Zimmer has experience in the NFC North. His Cowboys defense struggled in 2024, and got lit up by Detroit in Week 6, but the group dealt with several injuries.

Zimmer is known for employing an aggressive defensive style, which the Lions utilized under Aaron Glenn. With Brian Schottenheimer being named the new head coach, time will tell if Zimmer is ultimately retained on staff, and if not his experience could be valuable.

David Corrao

Current position: Detroit Lions Outside Linebackers Coach/Defensive Assistant

Corrao is truly an under-the-radar name amongst those currently on the Lions' staff. He's in his seventh season with the organization, and he has worked with Kelvin Sheppard to direct the linebackers for the last three seasons.

He also worked with Campbell in Miami, spending eight seasons with the Dolphins in total from 2008-15. During that time, he actually coached Sheppard as the team's linebackers coach while Sheppard was playing for the team.

Corrao's experience makes him an underrated candidate for a promotion, and at the very least he could step up to helm the linebackers if Sheppard is the one to land the coordinator gig.

Christian Parker

Current position: Philadelphia Eagles Passing Game Coordinator/Defensive Backs Coach

In his first season with the Eagles, Parker is on the cusp of helping his team get to the Super Bowl. Prior to going to Philadelphia, he spent the previous three seasons working with the Denver Broncos as their defensive backs coach.

As a result, he has been exposed to some of the game's best in that area such as Surtain, Justin Simmons and most recently Darius Slay. This experience could be very beneficial for Detroit, which currently boasts a talented secondary of its own led by All-Pro safety Kerby Joseph.

Ryan Nielsen

Current position: Jacksonville Jaguars Defensive Coordinator

Nielsen cut his teeth at the collegiate level before breaking into the NFL with the New Orleans Saints. He was on staff under Payton at the same time as Campbell and Glenn, joining the team as the defensive line coach in 2017.

When Campbell left, Nielsen took over assistant head coach duties in 2021 and was promoted to assistant defensive coordinator a year later. He spent a year with the Atlanta Falcons as the defensive coordinator in 2023 before going to Jacksonville this past season.

With Liam Coen taking over the head coaching job in Jacksonville, it's uncertain whether Nielsen will remain with the team. As a result, he's a candidate worth evaluating in this year's search.