‘Assuming new defensive coordinator Jim Leonhard sticks with his background, the Bills will be moving back to a 3-4 base defense. Leonhard, born from the Ryan-Pettine tree, won’t be running the 3-4 defense the Bills ran from 1979-2000, nor even the one Pettine and Ryan ran. It will feature multiple fronts, and frankly, base defense isn’t really the base anymore. Defensive personnel shifts with offensive personnel from game to game and play to play.’