Fangio is a disciple of current Green Bay Packers defensive coordinator Dom Capers, and the system the Cardinal runs is really an adaptation of what the Steelers, Packers, and other “one-gap” 3-4 teams do. (To oversimplify, “one gap” means each defensive player is responsible for a gap between offensive players, while a “two-gap” system — which is more common for 3-4 defenses — requires defensive linemen to attack blockers instead of gaps and control gaps to either side while the linebackers are free to roam.)