4-3 Defense
The most common run defense at nearly every level — four down linemen, three linebackers — built entirely on one-gap control where each front defender owns exactly one gap.
Best fit
For older youth teams with athletic, disciplined linebackers who can handle one-gap reads. Better once players have progressed past the basics.
Base formation & personnel
4 down linemen (a nose shaded on the center, a DT on a guard, two DEs on the tackles' outside shoulders); 3 linebackers (Sam/Mike/Will); 4 defensive backs (two corners + two safeties).
Core philosophy
- →One gap per front defender — everyone attacks a single responsibility.
- →Three linebackers flow to fill the rest.
- →A safety can drop to add an eighth run defender in Cover 3.
- →Sound and scalable — the standard for older youth.
Gap & technique assignments
- →Nose: shade the center; backside A gap.
- →Tackle: outside shoulder of a guard; B gap.
- →Ends: outside shoulder of the tackle; C gaps.
- →Linebackers (Sam/Mike/Will): each fills an assigned gap; the Mike is the run-fit anchor.
Run fits
A strong, disciplined one-gap run defense — each lineman controls his gap and the three linebackers flow to fill. In Cover 3 a safety can drop to add an eighth run defender.
Coverage basics
Very flexible — pairs naturally with Cover 3 (three-deep zone) or Cover 1/Cover 2 at higher youth levels. Zone is recommended for younger groups.
Full Playbook
28 playsA complete install menu — every play/call grouped by type. Tap any play for a full breakdown: every position's job, how to teach it, and common mistakes to fix.
Short-yardage adjustment adding a fourth backer to load the box at the goal line.
Key: An extra backer walks into the box and all defenders fire their gap low to stop the dive and sneak.
Full breakdown →Deep-drop prevent coverage guarding against the big play late in a half.
Key: Defenders bail to deep quarters and keep all receivers in front, tackling in bounds to run the clock.
Full breakdown →Passing-down personnel swapping a backer for a nickel back with two-deep coverage.
Key: The nickel covers the slot while two safeties split the deep halves against pass-heavy sets.
Full breakdown →Standard 4-3 with the three-technique shaded to the strong side for a balanced front.
Key: Strong tackle plays a 3-technique on the guard's outside shoulder while the nose plays a shade on center.
Full breakdown →4-3 alignment shifting the line weak with the three-technique to the weak side.
Key: The nose shades strong and the 3-technique tackle moves to the weak-side guard, dropping the Sam onto the line.
Full breakdown →The Mike linebacker blitzes downhill through the A-gap.
Key: Mike triggers on his read and fires the open A-gap while the tackle slants away to clear the lane.
Full breakdown →The weak-side Will linebacker blitzes through the B-gap.
Key: Will attacks the B-gap off the tackle's hip while the end crashes inside to occupy blockers.
Full breakdown →The strong-side Sam linebacker blitzes off the edge for contain pressure.
Key: Sam attacks the tight end's outside shoulder keeping outside leverage to force runs back inside.
Full breakdown →Mike and Will blitz both A-gaps for heavy interior pressure.
Key: Both backers fire the A-gaps while safeties rotate to the middle and ends contain the edges.
Full breakdown →The strong safety blitzes off the edge or interior gap.
Key: Strong safety walks up late and fires his gap while coverage rolls to single-high behind him.
Full breakdown →A cornerback blitzes off the edge from press alignment.
Key: The corner times the snap off the receiver's release while a safety rotates over the top to his man.
Full breakdown →The nickel defender blitzes off the slot for pressure on passing downs.
Key: The nickel fires off the slot receiver's edge while a safety rotates to cover the slot deep.
Full breakdown →Mike and Will blitz while crossing faces to beat man protection.
Key: The two inside backers cross through opposite A-gaps to confuse the interior blocking rules.
Full breakdown →Five-man pressure with a three-deep, three-under zone behind it.
Key: A backer or nickel blitzes while a defensive end drops to cover the vacated underneath zone.
Full breakdown →Both tackles pinch into the A-gaps to clog the interior run.
Key: Tackles slant off the guards' inside shoulders into the A-gaps while ends hold contain.
Full breakdown →Both defensive ends crash inside to the B-gaps to squeeze inside runs.
Key: Ends slant into the B-gaps while the outside backers scrape over the top to take contain.
Full breakdown →The four-man front slants to the strong side to overload that gap set.
Key: Each lineman steps to his strong-side gap on the snap, shifting the front one gap over.
Full breakdown →The four-man front slants weak to jump backside runs.
Key: Each lineman steps to the weak gap while backers flow over the top to fill behind them.
Full breakdown →A tackle and end on the same side exchange gaps to beat pass protection.
Key: The tackle penetrates the B-gap first while the end loops behind into the vacated inside gap.
Full breakdown →An end and tackle exchange with the end crashing first and tackle looping out.
Key: The end crashes inside to the B-gap while the tackle loops around to the vacated C-gap edge.
Full breakdown →Four-man front with three-deep zone coverage behind three linebackers.
Key: Both corners and free safety cover the deep thirds while backers and strong safety cover underneath.
Full breakdown →Four-man front with two safeties splitting the deep halves.
Key: Safeties defend the deep halves while corners sink to the flats and the Mike carries the deep middle hole.
Full breakdown →Cover 2 variation with the Mike linebacker dropping deep to defend the middle hole.
Key: The Mike sprints to the deep middle between the two safeties while corners and other backers play the underneath.
Full breakdown →Man coverage with a single free safety over the top and a robber underneath.
Key: Corners and backers play man while the free safety plays center field and a backer robs crossers.
Full breakdown →All-out man coverage with no deep help for a maximum blitz.
Key: Every receiver is matched man-to-man freeing both safeties to blitz or add to the rush.
Full breakdown →Four-deep zone splitting the field into quarters against spread pass sets.
Key: Corners and safeties each defend a deep quarter and read the number-two receiver for run-pass keys.
Full breakdown →Three-deep zone with the strong safety rolling down to the flat.
Key: Strong safety fills the strong flat while free safety and both corners cover the deep thirds.
Full breakdown →Three-deep zone with the corner dropping to the flat instead of the safety.
Key: The cloud corner sinks to the flat while a safety rotates over the top to cover that deep third.
Full breakdown →More defense systems
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