Playbooks
Mtn Empty Dbl Unders is an Empty backfield formation play out of the Shotgun Y Off Trips Pats set that uses a motion tag to shift protection and coverage recognition pre-snap. The concept features double underneath crossing routes designed to sit in the shallow zones or settle in the void created by man coverage, paired with vertical clear-out routes from the outside receivers that occupy the deep safeties and cornerbacks. This is primarily a zone beater built to attack Cover 3 and Cover 2 hole defenders, though it also holds up against man coverage because the double unders create natural rub and separation leverage. The primary read progression starts with the underneath crossers working from the trips side, then works to the backside dig or shallow drag if linebackers sink into the throwing lanes.
Pre-snap, check the safety alignment for two high versus one high shells, since two high safeties often signal Cover 2 or Cover 4 which leaves the underneath crossers open in the seams between zone defenders. Watch linebacker depth at the snap, if they sink too deep into coverage the shallow crossers will have a wide throwing lane underneath, if they stay shallow you can hit the deeper option breaks behind them. Man coverage with press corners on the outside receivers is the biggest threat to this play because it removes the natural rub advantage created by the crossers, so be ready to check into a quicker underneath throw before the corners recover. User-controlled defenders sitting in the middle hook zone or lurking as a rat in the shallow area can jump the double unders route, so look for that user movement post-snap and be ready to reset the throw to the backside route. Cover 3 with a single deep defender and aggressive underneath zone drops is the toughest shell to beat with this concept because it clogs both crossing lanes, in that case consider audibling to a play with more vertical stretch like Mtn Empty Smash Y-post instead.
Use the pre-snap motion to identify man versus zone before the snap, if the defender follows across the formation you know you are getting man coverage and can hot route the double unders into option routes to sit versus zone or break away versus man. This play excels on second and medium to third and short because the underneath crossers give you a high floor completion while the vertical routes keep safeties honest. Combine this play with Mtn Empty HB Sluggo and Mtn Empty Smash Y-post from the same set to keep defenders guessing between quick underneath throws and shot plays off similar Empty alignment. If the defense shows Cover 3 shell pre-snap, hot route one of the crossers into a deep sit read behind the linebackers to punish the middle zone defender who has to choose between the two crossing routes. Against aggressive man blitz teams, use the motion to check into a quicker rhythm throw since the double unders release fast and beat off man leverage before pressure arrives.