The Detroit Lions will need to find a new leader for their defense after Aaron Glenn’s departure to coach the New York Jets. This marks the first time in Dan Campbell’s tenure that he’ll be seeking a new defensive coordinator. While there are some promising internal options, such as linebackers coach Kelvin Sheppard, the Lions may also explore external candidates.
The team has already begun the search, interviewing 14-year NFL veteran and Michigan native Larry Foote for the role earlier this week.
Here are five lesser-known candidates for the Lions to consider as they look ahead to the 2025 season:
Jim Leonhard
Current position: Denver Broncos Defensive Pass Game Coordinator/Defensive Backs Coach
Leonhard has a connection with Dan Campbell from their time together in New Orleans. He later served as defensive coordinator and interim head coach at Wisconsin before returning to the NFL. In his first season with the Broncos under Sean Payton, he worked closely with standout corner Patrick Surtain.
Having played 10 years in the NFL, Leonhard, who started as a walk-on at Wisconsin, embodies the Lions’ gritty mentality and fits their preference for former players on staff.
At Wisconsin, Leonhard’s defenses were consistently strong, and his scheme could work well at the NFL level. His experience under longtime coordinator Vance Joseph strengthens his case.
Mike Zimme
Current position: Dallas Cowboys Defensive Coordinator
Zimmer, former head coach of the Minnesota Vikings, is no stranger to the NFC North. Although the Cowboys’ defense struggled in 2024, especially against Detroit in Week 6, injuries played a role.
Zimmer is known for his aggressive defensive style, which aligns with the approach the Lions used under Glenn. If he’s not retained under new head coach Brian Schottenheimer, Zimmer’s experience could still be a valuable asset.
David Corrao
Current position: Detroit Lions Outside Linebackers Coach/Defensive Assistant
Corrao is a relatively unknown name within the Lions’ staff but is an experienced candidate. In his seventh season with Detroit, he has spent the past three years working alongside Kelvin Sheppard to coach the linebackers.
Corrao also worked with Campbell in Miami, coaching Sheppard during his playing days with the Dolphins. His extensive experience makes him an underrated option for a promotion, and he could take over the linebackers if Sheppard is promoted to coordinator.
Christian Parker
Current position: Philadelphia Eagles Passing Game Coordinator/Defensive Backs Coach
In his first season with the Eagles, Parker is on the verge of helping the team reach the Super Bowl. Before joining Philadelphia, he spent three years as the defensive backs coach for the Denver Broncos.
During his time with the Broncos, Parker worked with top talents like Patrick Surtain, Justin Simmons, and Darius Slay. This experience could prove valuable for Detroit’s own strong secondary, which is led by All-Pro safety Kerby Joseph.
Ryan Nielsen
Current position: Jacksonville Jaguars Defensive Coordinator
Nielsen began his career in college before making the jump to the NFL with the New Orleans Saints, where he worked alongside Campbell and Glenn. He joined the Saints’ staff in 2017 as the defensive line coach and later took on assistant head coach duties in 2021 before being promoted to assistant defensive coordinator.
Nielsen spent a year as the defensive coordinator for the Atlanta Falcons in 2023 before joining Jacksonville. With a new head coach in Jacksonville, it’s unclear whether Nielsen will remain with the team, making him a candidate worth considering in the Lions’ search.
