ORCHARD PARK, N.Y. — The Buffalo Bills are overhauling their defensive scheme under new coordinator Jim Leonhard, and players say the change requires relearning how they play. Defensive tackle Ed Oliver compared the shift to a breakup, saying, “Everything you did in the last relationship, yeah, throw that all that away.” The team is installing the system during voluntary organized team activities (OTAs).
Leonhard, in his first NFL defensive coordinator role, spent six seasons as Wisconsin’s defensive coordinator from 2017-22 and spent 2024-25 on the Broncos’ coaching staff, according to the team. He is moving the Bills from a 4-3 to a 3-4 base and described balancing his vision with the current roster’s skill sets. “I had a vision for what I want it to be, and it might not totally get there in year one,” Leonhard said. “We have to be real as far as who we have, what their skill sets are, and I have to be flexible as well as them.”
Leonhard said the unit will be dialed in farther once training camp approaches and acknowledged the defense could evolve over the course of the season. He described using an “overload” approach in teaching, pushing extensive information onto players to create discomfort and force more communication as the scheme takes shape.
The new base defense should change roles for some players. Leonhard said the 3-4 will give Oliver more freedom and create opportunities to isolate guards for one-on-ones. Oliver pointed to defensive lineman Zach Allen’s production in Denver while Leonhard was on that staff — Allen totaled more than 40 quarterback hits and at least seven sacks in both 2024 and 2025 — and said he hopes for similar success.
Oliver has battled injuries the past season, including a left ankle issue before Week 2, a torn left biceps in Week 8 and meniscus damage while rehabbing in December. He said he is healthy now, missed a recent on-field session because of a minor incident he called a “little oops-oops,” and expressed optimism about the change. Teammate T.J. Sanders said Leonhard’s scheme should allow some players to better play to their strengths because of increased one-on-one opportunities.
