Playbooks

H Close Off takes the Weak I shell and pulls the fullback out of the traditional offset alignment, closing him tight next to the tackle on the strong side as an H-back style blocker while the halfback stays stacked behind the quarterback. That single alignment change flips the run math: instead of a lead blocker attacking the weak side hole, you get an extra body at the point of attack on the closed side, which is why HB Gut, Power O, and Counter F all hit with real force out of this set. The receiver split leaves a lone flanker isolated to one side, so you are effectively running a pro style two back look with a built in one on one on the boundary.
The 21 personnel tag matters because most opponents will answer it with base 4-3 or nickel and keep a safety in the box. That gives you leverage in two directions. On the ground, the closed H-back seals the edge defender so Power O and PA Power O pull cleanly, and Counter F gives you a misdirection answer once the user starts flowing hard to the initial run key. Through the air, Verticals and Flanker Drive punish that loaded box because you are asking a linebacker or a strong safety to carry a back out of the backfield or handle a crossing route with no help underneath.
Where H Close Off separates itself from other Weak I sets is the pass distribution. Bench Switch and Stick both give you defined quick game reads that do not require a five step drop, and 94 Will is the play action shot that sells inside power before releasing routes down the field. Combined with the Gadget and 3DRB tags, this set lets you stay in one alignment and run heavy ground concepts, third down passing concepts, and trick plays without ever tipping the call through personnel swaps.
Open with HB Gut and Power O on first and second down to force the box to load, then flip to PA Power O and 94 Will on the same down and distance to hit the vacated intermediate zones.
Check the flat defender's alignment before snapping Stick: if he is squatted at the numbers, take the stick route inside, if he widens, throw the flat immediately.
On third and medium, hot route the halfback to an angle route out of Bench Switch to give yourself a man beater when you read a single high shell with tight corners.
Use Verticals against Cover 1 or Cover 0 looks and target the isolated flanker, but motion the fullback to widen the box read if you need to confirm man coverage pre snap.
Counter F is your answer once the user starts jumping the initial power flow, so save it for a situation where you have already run Power O twice from the same look in the drive.