Playbooks

Flanker Spot is the classic Spot concept run from Shotgun Tight Y Off Wk, a Cover 3 beater built to flood the underneath zones. The backside receiver runs a corner route up the sideline while the flanker attacks the middle on a deep dig, the outside receiver on the strong side runs a quick hitch, the TE releases into a corner route, and the HB checks out of the backfield into a flat/wheel route underneath. Primary progression starts with the flat/hitch combo to attack the underneath defender, then works to the spot/dig sitting down in the zone window, with the corner route as a low-percentage shot if a single-high safety cheats down.
Identify single high versus two high safeties before the snap, since Cover 3 is the primary shell this play is designed to exploit. Watch the flat defender post snap, if he sinks with the hitch or squats too far outside the spot route will be wide open underneath. Key the middle linebacker or hook defender drop depth, a shallow drop leaves the dig route soft and throwable immediately. Against Cover 4 or Cover 2 shells the corner route becomes contested, so expect the quarterback progression to stay short and underneath. User linebackers sitting in the flat or spying the HB checkdown can jump the shorter routes, so disguised blitzes or a lurking defender in that zone shut this concept down fast.
Use this on early downs or third and short where zone coverage is likely so the spot route can sit in the soft area between the flat and hook defenders.
Read the pre-snap safety alignment first, if you see two high safeties rotate to Cover 3 post snap this concept has an even easier window underneath.
Hot route the HB to stay in and block against exotic pressure looks if the offensive line count is even, since the flat route is only useful if you have time to read it.
Pair this with Smash Drag or Smash X-drag from the same set so defenses cannot sit on the flat/corner combo, forcing them to respect vertical shots too.
Against man coverage look immediately to the corner route or the deep dig for a natural pick or rub against trailing defenders rather than forcing the flat throw.