Playbooks

Four Verticals out of Pistol Wing Slot sends four receivers vertical in a true clear-out concept: the outside receiver runs a boundary seam, the TE from the wing releases up the numbers, the inline TE breaks outside near the sideline off a vertical stem, and the backside X runs a straight go route up the opposite boundary. There is no play-action or RPO element shown, this is a pure dropback pass with the RB staying in to help protect. Progression starts with the seam route matched against the deep middle defender, then works to the outside verticals if the safety shell rotates away, with the HB check-down available late if all four verticals are covered.
Pre-snap, check safety depth and alignment, if both safeties are shaded deep and wide it signals Cover 2 or Cover 4 and the seam window will be tight but exploitable with timing. Watch for a single high safety rotating to the middle of the field, which indicates Cover 3 or Cover 1, and tells you to attack the vacated seam or the side away from safety help. Post-snap, key the middle linebacker's drop, if he sinks deep into the seam quickly this is a zone shell designed to take away the inside verticals, so shift focus outside. Look for user-controlled defenders lurking in the intermediate zone trying to jump the seam route, if the user bites on the underneath route, the outside verticals will be wide open for a big gain. Beware of Cover 1 or Cover 0 blitz packages that show press man across the board, since a well-timed blitz can beat the four verts route combo before routes fully develop, so be ready to check down to the HB quickly.
Pre-snap, identify if the defense shows two deep safeties or one, since this route combo is built to punish Cover 2 and Cover 3 shells that cannot cover four vertical stems with only two or three deep defenders.
Against Cover 2, target the seam routes in the honey hole between the corner and safety before the safety can get over the top.
Against Cover 3, work the vertical routes on the side where the corner is playing a deep third alone, since he has no help underneath from the flat defender.
Use hot routes to convert one vertical into a comeback or hitch if you see aggressive man press, giving you a quick throw beater instead of forcing the deep ball into tight coverage.
Pair this play with Y Stick or HB Slam earlier in a series to get the defense to bite on shorter routes, then come back to Four Verticals to hit the defense over the top once linebackers and safeties start creeping up.