Playbooks

Pistol Open Flex takes the standard Pistol depth (quarterback four yards deep, back stacked three yards behind him) and spreads it out with 11 personnel: one running back, one tight end, and three receivers. What separates Open Flex from the tighter Pistol sets is the flexed tight end. Instead of attaching him to the tackle as an extra run fitter, Open Flex splits him out into the slot or wide, which forces the defense to declare coverage on him before the snap. If a linebacker walks out over the flexed tight end, you have your matchup. If a safety rotates down instead, you just gutted the run fit and the Read Option and Counter F become live.
The set is tagged Gadget for a reason: the Pistol alignment hides run direction until the mesh point, so HB Zone Wk, Inside Zone Split, and Read Option all present the same backfield picture. Because the back is directly behind the quarterback rather than offset, defenders cannot key the run to the strong or weak side off alignment alone, which makes the counter and split zone concepts significantly harder to fit than they are out of Singleback or Gun offset looks. Read Option in particular punishes any user who overcommits an edge defender.
The pass game leans heavily on play action, and that is where Open Flex separates itself from the rest of the Pistol tree. PA Boot, PA Boot Rt, and PA Double Post all sell the same downhill run action before moving the pocket or attacking the deep middle. Slants and Verticals give you the quick game and vertical stretch to keep coverage honest. With three receivers plus a flexed tight end, you can isolate your slot mismatch against a linebacker on any Slants or option route hot route while the outside receivers clear the boundary.
Read the defender aligned over the flexed tight end before anything else. Linebacker or safety in the box means attack with Slants or a hot routed option route. Nickel or corner means the box is light, so hand off on HB Zone Wk or Inside Zone Split.
Use PA Boot and PA Boot Rt on second and medium after establishing the zone run game. The play action freeze plus the moving pocket beats interior pressure and gets your quarterback outside the rush lane.
Save PA Double Post for third down against two high shells. Confirm the safeties stay deep post snap, then work the post opposite the safety rotation.
Hot route the flexed tight end to a drag or in route when you diagnose man coverage, and let the outside Slants clear the coverage above him for the natural rub.
Mix in Read Option when your opponent starts user controlling the edge or committing a defender to the back. The keep punishes overcommitment and forces them to play honest for the rest of the series.