Playbooks
X Under
Breakdown
X Under is a play-action flood concept out of Shotgun Trips TE Offset that overloads one side of the field with five distinct route levels. The backside single receiver runs a go route on play-action to hold the deep safety, while the trips side stacks a corner route, a deep drag, an out, and a flat route from the backfield to create a five-level stretch. The fullback or offset TE fakes a run block before the QB rolls his eyes through the flood, reading flat to out to drag to corner. This is a zone beater designed to stress Cover 3 and other zone shells by putting more receivers in a zone than there are defenders, though the underneath crossers also give it man beater traits versus man coverage with picks and natural separation.
Defensive Reads
Pre-snap, identify the deep safety count: one high safety signals Cover 3 or Cover 1, both of which this flood concept is designed to attack with the corner and drag routes. Watch the flat defender at the snap since the flood puts a receiver in the flat, the out, and the corner all in the same third, meaning a single defender cannot cover all three. As a defender, key the underneath linebackers dropping to the drag route, since a lurking linebacker who sits in the shallow zone can jump the drag and force the QB to hold the ball longer. Two deep safeties with press corners at the line indicates Cover 2 or Cover 4, which can take away the corner route with the deep safety help, forcing the QB to check down to the flat or drag. Watch for slot corner blitzes off the trips side, since the flood concept has a hot route built into the flat route to beat pressure if the blitz comes from that alignment.
Usage Tips
Check pre-snap for two deep safeties versus one high, since a single high safety with Cover 3 underneath zones is exactly what this flood concept is built to punish.
Use the play-action fake to freeze linebackers for an extra beat, giving the drag and out routes time to sit down in soft spots between zone defenders.
Hot route the backside go route into a slant or comeback if you see man coverage rolled to that side with no safety help, turning it into a quick throw versus a blitz look.
Pair X Under with Curl Combo or Levels Sail in your play-calling sequence so the defense sees similar route stems and formation but has to guess between a flood concept and a levels concept.
Best called on second and medium to third and long when you expect zone drops, since the flat to corner combo picks apart soft zone coverage that sits off the line.
