Jim Leonhard is stepping into the NFL coordinator ranks for the first time, but don’t let the “rookie” label fool you-this guy knows how to build a defense.
During his six-year run as Wisconsin’s defensive coordinator, Leonhard consistently fielded one of the toughest units in college football. Five top-10 finishes in total defense, including two seasons leading the nation, speak volumes about his ability to scheme, teach, and get the most out of his personnel. That kind of track record doesn’t happen by accident.
Now, after a stint learning under Vance Joseph in Denver, Leonhard is taking the reins of a Buffalo Bills defense that’s been strong in the regular season but hasn’t quite delivered when it matters most. The pieces are there, but the Bills clearly believe Leonhard can elevate the unit to another level-and history suggests he just might.
As free agency approaches, don’t be surprised if Buffalo looks to bring in a few familiar faces to help smooth the transition. Here are some names with ties to Leonhard that could be worth watching.
Leo Chenal - Linebacker, Kansas City Chiefs
Chenal was a game-wrecker under Leonhard at Wisconsin. Back in 2021, he posted eye-popping numbers: eight sacks, 17.5 tackles for loss, 114 total tackles, and two forced fumbles in just 11 starts. He was the heart of that defense, flying around the field with a mix of power and speed that made him a nightmare for opposing offenses.
Since joining the Chiefs, Chenal has carved out a role as a physical run-stopper and situational blitzer. But his growth in coverage and overall versatility suggest there’s more in the tank.
A reunion with Leonhard in Buffalo could unlock that next level. If the Bills are looking for a linebacker who already knows the system and brings a physical edge, Chenal fits the bill perfectly.
Jack Sanborn - Linebacker, Dallas Cowboys
Another former Badger, Sanborn was a steady presence under Leonhard. His final season in Madison saw him rack up 91 tackles, including 16 for loss, and five sacks. He was the kind of linebacker who always seemed to be in the right place at the right time.
Sanborn’s NFL journey has been a bit rockier. After three seasons with the Bears, he signed a one-year deal with the Cowboys but struggled to stay on the field, appearing in just six games and recording 34 tackles.
Still, for a team looking to add depth and familiarity to the linebacker room, Sanborn could be a low-cost, high-upside option. He knows Leonhard’s system and brings a smart, disciplined approach to the game.
Alex Singleton - Linebacker, Denver Broncos
Singleton is the kind of linebacker coaches love: tough, relentless, and always around the football. He’s logged 120+ tackles in five of the last six seasons, which tells you everything you need to know about his consistency and durability. And Bills fans certainly remember him-he’s the one who forced that early James Cook fumble in Buffalo’s playoff loss to Denver.
His path to NFL success wasn’t linear. After going undrafted out of Montana State, Singleton bounced around practice squads before heading north to the CFL.
There, he became a star with the Calgary Stampeders, earning two CFL All-Star nods, a Grey Cup title, and the league’s Most Outstanding Defensive Player award in 2017. That experience shaped him into the player he is today-a blue-collar, high-motor linebacker who just keeps producing.
If Buffalo wants a veteran presence to anchor the linebacker corps and help implement Leonhard’s vision, Singleton would be a strong fit.
P.J. Locke - Safety, Denver Broncos
Locke is a name to keep an eye on, though prying him away from Denver might not be easy. He’s made it clear he’d love to retire a Bronco, but in the NFL, opportunity often trumps sentiment-and Buffalo could offer just that.
In 2025, Locke found himself behind Talanoa Hufanga and Brandon Jones on the depth chart. But when Jones went down in mid-December, Locke stepped in and made the most of it.
He delivered in the postseason, recording a pick and a forced fumble in Denver’s win over Buffalo. That kind of clutch performance doesn’t go unnoticed.
Leonhard could pitch Locke on a starting job next to rookie safety Cole Bishop. At 29, Locke may be ready for a bigger role, and Buffalo could use a veteran presence on the back end of their defense.
John Franklin-Myers - Defensive Lineman, Denver Broncos
Bills fans are plenty familiar with Franklin-Myers from his days with the Jets, and he’s only gotten better since landing in Denver via trade during the 2024 NFL Draft.
In two seasons with the Broncos, Franklin-Myers has been a force-14.5 sacks, 33 quarterback hits, and 14 tackles for loss. That’s the kind of production Buffalo could use up front, especially with some uncertainty around their current defensive line rotation.
He brings size, athleticism, and a relentless motor-traits that fit well in Leonhard’s aggressive front. If the Bills are looking to beef up their pass rush and bring in someone who can collapse the pocket from multiple alignments, Franklin-Myers would be a smart target.
Leonhard may be new to the NFL coordinator scene, but he’s no stranger to building elite defenses. With a few familiar faces and the right pieces already in place, Buffalo’s defense could be in for a serious resurgence. Free agency is always a bit unpredictable, but don’t be surprised if Leonhard taps into his past to help shape the Bills’ future.