All the successful outside zone-play-action offenses are leading to more split-safety coverage structures, five-man fronts, and faster defenders at the second level who can fast-flow to the perimeter and recover to passing landmarks off play-action. As defenses have gotten lighter and better equipped to combat outside zone, offenses are adjusting, with even Kyle Shanahan and Sean McVay majoring in more duo/gap schemes to run downhill into lighter boxes against stretched-out defenses.
Former head coach Bill Belichick had a hand in this shift in philosophy. In Super Bowl 53, Belichick shut down the Rams high-powered offense by unveiling a 6-1 tilt front to set the edge against McVay's outside zone schemes. With six defenders across the line of scrimmage, the Patriots defense funneled the ball back inside toward their big DTs and run-stuffing linebackers. In the secondary, the Pats played both quarters and cover-three buzz to limit big plays off play-action. Eventually, it put the game in a young Jared Goff's hands in obvious passing situations, and the Patriots won the duel.
McVay and others from the West Coast/outside zone family had to adjust to stay relevant. The answer was to call more gap schemes and add blockers to flip the formation's strength on the fly with motion. For Cleveland, they became a gap-based run scheme. Over the last two seasons, the Browns lead the league in how often they use man-blocking and heavily feature schemes with pulling linemen.