The play is known as a "trap" because the strong side offensive lineman will "block down" on a linebacker, seemingly leaving a defensive lineman unblocked. As the defensive lineman comes through the seemingly open gap/hole, he is "trapped" by the weak side (also known as backside) guard who blocks the defensive lineman's blindside.

On a trap play, the offensive line leaves a defensive lineman unblocked in hopes that he’ll fly upfield, so a pulling offensive lineman can earhole him to open up a hole for the ball carrier inside. It’s an old-school play that is still run sparingly in the NFL. When called at the right time, a trap usually leads to an explosive run.

Trap hits fast and needs to be timed well with narrow running lanes for the running back down the middle of the defense. With a shorter distance to pull, trap is a fast play that intentionally leaves an interior defensive lineman unblocked. That defensive tackle then gets “trapped” by the pulling backside guard.

Trap is a quick-hitting, downhill run scheme that kicks out an interior Defensive Lineman and is especially effective against an aggressive pass rushing defensive lineman. If an offense has a bruising, powerful Fullback, it can be just as successful as a Spread offense that has a smaller, more dynamic Tailback running Trap.

The trap run, though, allows the right guard to immediately sprint and pick up the Mike. b. Keeps the defense guessing Second, the trap run works because it causes defensive tackles to always be on the lookout for traps on future plays. Once you run the trap, the defensive tackle knows that you might run it again.