Duo

Each offensive lineman checks his inside gap first. If there is a defender in the inside gap, he blocks that man one-on-one. If the inside gap is empty, he turns to the defender in his outside gap and joins the adjacent lineman for a double-team. The goal is to create two vertical double-teams that drive defensive linemen 3-4 yards off the ball. The uncovered linemen eventually peel off the double-team to block a scraping linebacker. The key coaching point is vertical push, the double-teams must move north-south, not laterally.

Read the MIKE linebacker. If the MIKE plugs the B-gap between the double-teams, bounce to the outside gap or cut back to the weak side. If the MIKE scrapes over the top of the double-team (flowing laterally), hit the gap created by the vertical displacement and run downhill. The aiming point is the gap between the two double-teams. Be decisive, Duo is a one-cut, downhill play.

Duo overwhelms the defensive line with sheer vertical force. The two double-teams create massive displacement at the point of attack, when a 600-pound tandem drives a 300-pound defender backward, there is nowhere for the linebacker to fit. The RB's MIKE read ensures the offense always has an answer: no matter what the linebacker does, one gap will be open.

MIKE linebacker, the read key for the RB's cut decision. If MIKE fills downhill, the RB bounces; if MIKE scrapes laterally, the RB hits the vacated gap.

• Y-Cross · Duo play-action into Y-cross, the heavy run fake draws the linebackers downhill, opening the intermediate crossing routes behind them.

The Baltimore Ravens under offensive coordinator Greg Roman made Duo a foundational piece of their run game with Lamar Jackson. The scheme's emphasis on vertical double-teams perfectly complemented the read-option game, as the physical displacement up front combined with Jackson's keep threat created an almost unsolvable math problem for defenses.