In the NFL, some defensive schemes and plays are predicated on disguise to create confusion for quarterbacks after the snap. There are a variety of ways this can be done with post-snap shifts at all levels of the defense.
Here we'll examine one "disguised" coverage, a look featured in Sean McDermott's defense currently run by the Bills.
This isn't a type of coverage used frequently Buffalo runs, yet it's a facet of the playbook that's an integral wrinkle to the defense.
How Cover 3 Robber attempts to confuse quarterbacks
The base coverage in McDermott's system is Cover 3, which means the two outside cornerbacks are responsible for the two deep thirds on the outside while the free safety mans the deep middle.
Typically, that means the strong safety aligns closer to the line of scrimmage, and the free safety aligns where it would be logical for him to be before the snap – deep and in the middle of the field.
But in "Cover 3 Robber," the safeties begin even with each other on the back end to give a two-deep look. That usually indicates Cover 2, which after the snap, looks like this:
The horizontal lines illustrate where the outside corners stop their drops, as they're responsible for short throws into the flat.
When a quarterback peeks into the secondary and sees two deep safeties, he can assume both of them will be sinking into deep coverage.
Against a traditional Cover 2 defense, one "hole" is toward the sideline over the outside cornerbacks who sit down after a quick backpedal and the sinking safeties. The other hole is deep down the seam if the middle linebacker isn't fast enough in his drop.
Despite looking like a two-deep coverage, this is what happens after the snap in Cover 3 Robber.
The free safety runs diagonally to the deep middle, and the outside cornerbacks are responsible for the outside thirds like they would in a normal Cover 3 look.
The "Robber" is the other safety, in this diagram the strong safety, who "buzzes" down to the middle of the field behind the linebackers and assumes somewhat of a freelancer role.
He can locate and cover an underneath drag route, look to jump in front of a intermediate in-breaking route like a dig, or make a play on a seam route thrown by a quarterback who thinks he's finding a hole in Cover 2.
The post-snap rotation of the safeties can perplex opposing signal-callers and force them into bad decisions, and the Robber concept in Cover 3 is something worth watching when the Bills are on defense. Both Micah Hyde and Jordan Poyer have the skill sets to create big plays in the Robber role.