Playbooks

Mtn X Spot is a Cover 3 beater out of Shotgun Tight Open 11 personnel that uses pre-snap motion to shift the defense before the snap. Off the diagram, the X receiver runs a shallow flag/corner route to the boundary flat, one slot receiver runs a deep spot/hitch that sits in the void underneath the deep zone, and the backside receiver runs a vertical clearout to stretch the defense deep down the sideline. The single blue route on the opposite side is a checkdown or drag underneath, giving the quarterback a full-field progression: read the deep clearout to hold the corner and safety, then work the flag route on the boundary, and finally settle to the underneath spot or drag against zone leverage.
Pre-snap, key the corner over the X receiver, if he follows the pre-snap motion tightly it signals man coverage and you should sit on the flag route with your defender in phase. Watch the free safety depth before the snap, a single high safety at 10 to 12 yards signals Cover 3 or Cover 1, both of which are vulnerable to the flag and spot combo underneath. Post-snap, get an underneath linebacker or nickel defender to sink and wall off the spot route zone, forcing the quarterback to hold the ball and take a checkdown. If the offense uses the motion man as a decoy, have your flat defender squeeze the boundary to disrupt the flag route timing and force an errant throw. Beware of a two high shell rotating late to Cover 3, since that disguise can bait the quarterback into throwing the flag route into a closing corner for a turnover opportunity if you jump the route as the user defender.
Use the pre-snap motion to identify if the defense is playing man or zone, if the defender follows the motion man you know you are facing man coverage and can key the flag route as your first hot read.
Against Cover 3, throw the flag route into the boundary as soon as the corner sinks into his deep third, since the spot sits perfectly in the flat to intermediate void.
Save this play for third and short to third and medium situations where the spot route and flag route give the quarterback easy access throws underneath.
Pair Mtn X Spot with Mtn Curls Out N Up or Mtn PA Cross in the same set so the defense has to respect both the shallow flag concept and vertical shots off similar formation and motion look.
If the defense rolls a robber or shows a lurking linebacker sitting under the spot route, hot route the underneath drag deeper or check to the vertical clearout for a big play shot.