Playbooks

Mtn RPO Read Flat lines up from Shotgun Tight Open with 11 personnel and shows an inside zone run track for the HB straight ahead behind a five-man box blocking scheme. Backside of the formation shows a two-man flat concept: the outside receiver runs a shallow drag/flat route while the slot defender releases on an arrow-style route to the flat, giving the quarterback a horizontal stretch read outside the box. This is a true RPO, the QB reads the alignment and flow of the second level defender (the box safety or overhang linebacker) to decide between handing off the zone run or pulling and throwing the flat, making it effective against both light boxes and zone defenses that widen with the run flow.
Pre-snap, identify the overhang defender or slot corner responsible for the flat, his depth and leverage tell you if the arrow route will be open. Watch the box count and safety depth, a stacked box with 7 defenders signals the defense is selling out on run, favor the flat throw. Post-snap, key the flow of the second level linebacker, if he steps up hard to fill the run gap, the flat route behind him is the automatic pull-and-throw read. This beats man coverage looks where the flat defender bites on run action, and beats light boxes in zone coverage that cannot account for both the run gap and the flat simultaneously. It struggles against disciplined zone defenses that keep the flat defender patient or against user-controlled defenders spying the QB, since a smart user can rob the flat throw and still fill the run lane.
Check the box count before the snap, if there are 6 or fewer defenders in the box, lean run and let the zone hat count decide it for you.
Key the alpha defender (usually the flat/curl defender or overhang backer), if he crashes down on run flow, pull and throw the flat route immediately.
Use this on early downs (1st or 2nd and medium) to stay balanced, since the RPO tag keeps defenses honest against both run and pass blitzes.
Pair this with Read Option or Inside Zone from the same set to condition the defense to bite on run action, then mix in Mtn Curl Y-Option or Mtn Flood H-Choice off similar formation looks to punish overaggressive flat defenders.
Against Cover 2 or Cover 3 shells with a hard flat corner, favor the give since the flat throw window shrinks fast.