Gap-Down-Backer

The core blocking rule for gap-scheme runs like Power, Counter, and Buck Sweep. GDB is primarily executed on the frontside of the play (and across the backside of perimeter sweeps like Jet Sweep), where linemen execute a disciplined inside-out progression:

Gap

Block anyone penetrating your inside gap.

Down

If your inside gap is empty, block the defender aligned over the lineman inside you.

Backer

If nobody is down inside, climb to seal the second-level linebacker.

A defender aligned head up on you is intentionally skipped. In a gap scheme, a head-up defender is not an immediate threat to the interior running lane and is left on the line of scrimmage for a pulling guard's kick-out block. If a lineman mistakenly base-blocks a head-up defender, the puller has nobody to kick out and the linebacker runs unblocked through the vacated gap.

Why backside linemen typically do not follow GDB on interior gap runs: Traditional gap-scheme plays like Power and Counter require backside protection and pullers. If a backside tackle followed GDB on Power, checking inside and climbing to a linebacker would give the backside edge rusher an unobstructed path into the backfield to tackle the runner from behind. Backside linemen on those plays instead execute pull, block-back, scoop, and step-and-hinge assignments. However, on fast perimeter sweeps like Jet Sweep where the ball gets outside immediately, backside linemen use GDB to climb directly to second-level pursuit.

How the unit coordinates on Power (Playside GDB + Backside Protection & Pulling):

Playside Tackle (RT)

Down rule. Checks inside B-gap (finds 3-technique DT) and down-blocks on him to collapse the frontside interior. The edge defensive end is left untouched on the line of scrimmage for the puller.

Playside Guard (RG)

Backer rule. Checks inside A-gap (empty), checks down inside on the center (nose tackle is secured by the center's block-back), and climbs directly through the A-gap seam to seal the Mike linebacker.

Center (C)

Block-back assignment. Blocks back on the backside 1-technique Nose to protect the pulling guard's vacated gap.

Backside Guard (LG)

Pull and kick assignment. Pulls flat behind the center and kicks out the unblocked edge defensive end on the perimeter.

Backside Tackle (LT)

Step-and-hinge assignment. Steps inside to cut off B-gap pursuit and hinges to wall off the backside edge.

The ball carrier presses downhill through the C-gap running lane between the tackle's down block and the pulling guard's kick-out block.

Playbook Examples

• Trapinside run, backside guard pulls to trap the first man past the holeWing-T
• Buck sweepoutside run to the wing, both guards pullingWing-T