Playbooks

Z Spot out of Singleback Bunch Ace lines up three receivers tight to the formation with a lone X isolated to the backside. From the bunch, one receiver runs a vertical wheel to the corner, another sits down on a spot route breaking outside near the sticks, and the third runs a quick flat/out to the boundary, while the backside X releases on an out breaking route from the numbers. The RB stays in to chip and check release, and this is a classic Cover 3 beater built to flood one side of the field and overload the underneath zone defender with three-level stress.
Pre-snap, check the deep safeties: a two-high shell with soft corners signals Cover 3 or Cover 4, both of which this flood concept is designed to punish. Watch the flat defender post-snap since he has to choose between the spot route sitting down and the receiver working underneath toward the sideline, creating a natural conflict. If the defense shows Cover 1 or Cover 0 with press corners, the wheel route can get picked off its route by a physical corner, so be ready to check down to the RB. Look for a user-controlled linebacker sitting in the shallow hook zone as a lurk threat, since he can jump the spot route if the quarterback holds it too long. Blitz-heavy Cover 0 looks with no deep safety help are the biggest threat to this play, since the flood concept needs time to develop and a quick pressure package can force an early throw.
Pre-snap, identify if the corner over the bunch is playing off or bailing into a deep third, since that tells you if the wheel route will get a clean vertical release.
Use the spot route as your first read against Cover 3 or Cover 4 because it settles right in the hole between the underneath zone defenders.
If you see man coverage or a Cover 1 shell, hot route the flat runner into a quicker out or peel him into a shallow drag to beat trailing defenders.
Pair Z Spot with Spacing or Stick from this same set to keep the defense guessing between a flood concept and a quick-game concept, since both use similar bunch alignments.
Best called on 2nd or 3rd and short to medium, since the spot route sits right at the sticks and gives you a high-percentage completion versus zone drops.