4-3 Under
Weak-side shade, SAM on the edge
The 4-3 Under shifts the defensive line toward the weak side, moving the 3-technique to the weak B-gap and walking the SAM linebacker up to the line of scrimmage as a de facto defensive end. This front is built for the Tampa 2 coverage shell, creating a 5-man surface with strong-side edge pressure from the SAM. The under shift naturally creates a difficult run fit for offenses trying to run toward the strong side.
Player Assignments
Weak-side edge setter. Aligns as a traditional 5-technique and must be disciplined about maintaining outside leverage against both run and pass.
Under-shifted 3-technique now on the weak side. Primary interior penetrator, attacking the weak B-gap to disrupt the backfield.
Shaded to the strong side of the center. Controls the strong A-gap and anchors the interior. Must hold the point of attack to protect the MIKE.
Strong-side end with C-gap responsibility. Works in tandem with the SAM who aligns outside. Must squeeze down on power runs and rush contain on passing downs.
Walked-up edge rusher. Responsible for strong-side force/contain on runs and is a primary speed rusher on pass plays. The defining player of the Under front.
Fills the strong A- or B-gap against the run. In Tampa 2 coverage, drops to the deep middle hole, turning the coverage into a 3-deep shell.
Weak-side run fitter. Must be fast enough to scrape to the strong side if the run goes away. In coverage, handles the weak hook zone or matches backs out of the backfield.
Strengths
- • Ideal for the Tampa 2 coverage, giving the MIKE a clean drop to the deep middle
- • SAM as a walked-up edge rusher creates a 5-man pass rush surface
- • Under shift makes weak-side runs very difficult for offenses
- • Strong-side run fits are reinforced by the SAM and DE working together
Weaknesses
- • Strong-side B-gap can be soft if the MIKE is slow to fill
- • SAM must be a true edge rusher, limiting personnel flexibility
- • Vulnerable to strong-side power if the NT gets moved off the ball