Playbooks

Counter U out of Singleback Wing Slot 12 personnel is a power run play built to attack the edge with a pulling guard and misdirection footwork. The HB takes a counter step away from the play call before hitting the hole behind the pulling blocker, using a wham/kick out combo to seal the edge for a lane off tackle. This is a run play with no route concepts, so the read progression is purely on the OL flow: press the counter step, key the pulling guard, and cut off his block once the edge is sealed.
Watch for linebackers cheating hard to the play side pre-snap, since this indicates they are keying the counter action and could blow it up early. Look for the edge defender crashing down the line immediately at the snap, which signals the defense recognizes the counter and will spill it outside. If the defense shows a heavy box with an extra defender near the line of scrimmage, this play becomes risky since the numbers favor the defense. Man coverage on the backside with no extra flow support is the best matchup, since it removes a potential spy or rover from the counter lane. User-controlled defenders sitting in the hole or shooting the gap post-snap can diagnose and blow up the pulling guard's angle, so avoid calling this against defenses that consistently sim blitz or crash down.
Pre-snap, check the box count and make sure you have a numbers advantage before calling this against stacked fronts with extra linebackers.
Use this against aggressive defenses that flow hard to the initial step since the counter action is designed to freeze linebackers who overplay the backside.
Combine Counter U with Inside Zone Split or HB Dive early in a series to establish downhill tendencies, then hit Counter U to punish defenders who are keying run direction too fast.
Ideal down and distance is first and ten or second and short, since the misdirection needs time to develop and works best when the defense is not in an obvious pass-rush mindset.
Manually control the pulling guard if facing a defense that loves nano blitzes off the edge, since a user controlled blocker can adjust to seal a hard-charging DE or blitzing linebacker.