The Buffalo Bills are turning the page on a new era-and they’re doing it with a familiar face stepping into a critical role. Jim Leonhard is set to become the team’s next defensive coordinator under newly appointed head coach Joe Brady, according to a source familiar with the agreement. While the deal isn’t yet officially signed, all signs point to Leonhard taking the reins of a defense that’s seen both high-level success and recent growing pains.
Leonhard, 43, brings with him a strong résumé and a reputation for defensive acumen. He spent the past two seasons with the Denver Broncos, most recently serving as assistant head coach and defensive pass game coordinator. He’s the second Broncos assistant to join Brady’s new-look staff in Buffalo, following Pete Carmichael’s addition as offensive coordinator just a day earlier.
What makes this hire particularly intriguing is that there’s no direct connection between Brady and Leonhard-a rarity in a league where coaching trees often dictate staffing decisions. But the Bills are clearly prioritizing fit over familiarity as they look to retool a roster still very much in its competitive window.
Buffalo's season ended in heartbreak just two weeks ago with a 33-30 overtime loss to the Broncos in the divisional round. That loss marked the end of Sean McDermott’s nine-year run as head coach and ushered in a new chapter with Brady stepping up from his role as offensive coordinator. While Brady’s elevation brings continuity to an offense led by Josh Allen, the defense is due for a reset-and Leonhard will be the one leading that charge.
He inherits a unit originally built to reflect McDermott’s defensive philosophy, but now in need of a new identity. Bobby Babich, who held the coordinator role the past two seasons, left last week to take the same position in Green Bay. Leonhard steps in at a pivotal moment, with Brady publicly stating he wants the defense to match the aggressive, attacking style he plans to bring on offense.
That mindset will be crucial for a defense that, despite finishing seventh in total yards allowed, struggled mightily in key areas. Buffalo ranked 28th against the run and just 14th in sacks per pass attempt-a far cry from the kind of disruptive presence Brady envisions.
Contrast that with Denver’s defense, which led the NFL with 68 sacks last season for the second year in a row. That kind of pressure production is exactly what the Bills need more of, and Leonhard had a front-row seat to how it was built.
For Leonhard, this is more than just a job-it’s a return to where his NFL journey began. He played two separate stints in Buffalo during his 10-year career as a defensive back, including his first three seasons from 2005 to 2007 after going undrafted out of Wisconsin. He wrapped up his playing career in Cleveland in 2014 before quickly transitioning to coaching.
Leonhard returned to Wisconsin in 2016, climbing the ranks from secondary coach to defensive coordinator. His defenses in Madison were consistently among the best in college football, and he even served as interim head coach to close out the 2022 season after Paul Chryst’s departure. He spent the following year at Illinois, further honing his craft at the collegiate level before making the jump back to the NFL.
Now, he’s back in Buffalo-not as the undersized, undrafted safety fighting for a roster spot, but as the architect of a defense looking to recapture its edge. With Brady steering the offense and Leonhard tasked with reshaping the defense, the Bills are betting on a fresh blend of youth, experience, and vision to take them deeper into January-and maybe beyond.