Are there still 3-4 fronts that utilize “2-gap” concepts? The Patriots at times, and the Steelers in their base front, are 2 teams that come to mind. But in a passing league that places a defensive premium on pressuring the quarterback, the reality is, you have far greater pass rush flexibility and versatility out of 4-3 principles, but with 3-4 personnel. You want more athletic defenders, and you want them aligned in gaps so that they can penetrate more effectively. That’s the key. It’s a tactical combination of personnel and concept.