Quote
Deadpool
Staley's defense last year played Cover 3 35% of the time, they were in a split safety look 45% of the time.

Later on in that drive, 3rd and 10, rams rush 5, pressure collapses the pocket, Rams were in a split safety matchup zone with a ton of coverage. Adams was open against Ramsey, but Rodgers had to rush the throw, threw deep and missed. There the coverage was fine, the cushions that Morris played was dumb, but it worked.

this is not the exact play, but it illustrates nicely

the pink boxes are the "shell" call it the cover-2 shell or cover-4 shell---it doesn;t really matter
look how, in this case, the left safety rotates into the middle to "rob" causing this to be
Cover-2, look at the yellow circles. But, really, since they are matching routes, it's more like
Cover-1 robber man to man everywhere except the middle of the field safety and the robber

on the play you describe some of the stuff is similar, didn't feel like drawing it all again
but it is the quarters match zone concept.

Line up with the shell, whatever anyone wants to call it "shell look" cover-2 shell, cover-4 shell
rotate one safety into shorter middle one to the deep middle and boom, it's Cover 3 (or 1) robber
whatever you want to call it.