With the Buffalo Bills brass hiring former Denver Broncos defensive assistant Jim Leonhard as their new defensive coordinator, it also brings about a schematic change to the base defense. The Bills will be switching from the simple 4-3 scheme to a more aggressive version of the 3-4. And don't kid yourself, these defenses are not the same at all.
While Buffalo struggled at times to stop the run, this new hybrid scheme may be the change the Bills need to become a more complete unit in 2026. With this alongside a new but familiar face calling the plays, this could bring the Billls defense into elite status.
Bills new DC Jim Leonhard brings fresh reset to the Bills defense
1. How it works
With the Bills switching up their base defense to a 3-4 under Leonhard, they have the personnel built for the 4-3. But as coaches, they have to be able to adjust to their players' strengths. One of the biggest pluses with Leonard is that he has been running different types of the 3-4 since his days at the University of Wisconsin, where he ran a nickel 3-3-5.
2. How it affects Bills
To understand how the 3-4 is different from the 4-3, just think of it in terms of evens and odds. In the 4-3, it is comprised of four defensive linemen up front and three linebackers in the middle. This defense consists of smaller but faster defensive linemen and linebackers, whose mission is to sack the quarterback. To stop the run, the two interior defensive linemen or tackles must be able to clog the inside lanes, making the running back second-guess running up the middle.
3. Which players are affected?
Last year, with Bobby Babich and Sean McDermott at the helm, the Bills' front seven consisted of Ed Oliver and Deone Walker as the two defensive tackles, and Greg Rousseau and Joey Bosa as the two defensive ends. The three linebackers were Terrell Bernard, Matt Milano, and Shaq Thompson.
As for the 3-4, the evens and odds switch, which means there are three defensive linemen and four linebackers in the front seven. Unlike the 4-3, where the defensive linemen are lighter and faster on the edge, the nose tackle in the middle is a big, gigantic guy, with two bigger and quicker defensive ends on the other side. The two defensive ends are the one-technique (LDE) and the five-technique (RDE), while the nose tackle is the three-technique.
As for the four linebackers, they play like defensive linemen in a 4-3. The two OLBs are the players who come up and rush the quarterback, while the inside and middle linebackers come up at the second level to bring the ball-carrier down.
If we were to use this past season's lineup to play guys for the 3-4, it could consist of Deone Walker at the nose tackle in the middle, TJ Sanders at the one-tech defensive end, and Ed Oliver as the five-tech defensive end. The two outside linebackers could be Greg Rousseau on the left and Joey Bosa on the right, and the two in the middle could be Terell Bernard and Matt Milano.
4. Which style do teams prefer?
It all really depends on the team's personnel and how a defensive coordinator wants to attack an opposing team's offense. Most teams in the NFL play a 4-3 because you need faster defenses to compete against today's top athletes, who train all year-round.
On the flip side, if you're a team like the Pittsburgh Steelers that has basically run the 3-4 all their lives, stick to what works and don't change a thing.