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4-2-5 Shell Recruiting Guide (CFB 27): Who to Recruit and Why

204 plays charted19 positions on the board

4-2-5 Shell is a two-high match defense. It lives in even, four-down fronts on 84% of its snaps.

The snap counts put two interior linemen, two edges, two sub linebackers, and five defensive backs on the field at starter share. Sub packages are the base defense here.

The strip below shows every formation the book calls, grouped the way the play-call screen groups them. Tap any bubble for the recruiting answer at that spot, then use the board for the full read.

The formations, grouped like the play-call screen

BallknowerHQ — ballknowerhq.com — nickel-overLOSNickel Over4 DL / 2 LB / 5 DBFS1SS1CB1CB2CB3SUBLB1SUBLB2RRE1NT1DT1RLE1ballknowerhq.com
Nickel Over21 plays · 10.1%
BallknowerHQ — ballknowerhq.com — nickel-single-mugLOSNickel Single Mug4 DL / 2 LB / 5 DBFS1SS1CB1CB2CB3SUBLB2RRE1NT1SUBLB1DT1RLE1ballknowerhq.com
Nickel Single Mug18 plays · 8.7%
BallknowerHQ — ballknowerhq.com — nickel-wideLOSNickel Wide4 DL / 2 LB / 5 DBFS1SS1CB1CB2CB3SUBLB1SUBLB2RRE1NT1DT1RLE1ballknowerhq.com
Nickel Wide18 plays · 8.7%
BallknowerHQ — ballknowerhq.com — nickel-load-mugLOSNickel Load Mug4 DL / 2 LB / 5 DBFS1SS1CB1CB2CB3SUBLB1RRE1NT1DT1SUBLB2RLE1ballknowerhq.com
Nickel Load Mug15 plays · 7.2%
BallknowerHQ — ballknowerhq.com — nickel-load-dbl-mugLOSNickel Load Dbl Mug4 DL / 2 LB / 5 DBFS1SS1CB1CB2CB3RRE1NT1DT1SUBLB1SUBLB2RLE1ballknowerhq.com
Nickel Load Dbl Mug12 plays · 5.8%
BallknowerHQ — ballknowerhq.com — nickel-double-mugLOSNickel Double Mug4 DL / 2 LB / 5 DBFS1SS1CB1CB2CB3RRE1NT1SUBLB1SUBLB2DT1RLE1ballknowerhq.com
Nickel Double Mug9 plays · 4.3%

Tap a bubble for the recruiting answer at that spot. Snap shares under each formation are that call's slice of the book.

The sign plan

Counts cover positions at 5% of the book's snaps or more. Bodies per snap decides how many each group needs. Each card jumps to its group on the board.

The board, by position group

Edges Sign 4: 2 starter, 2 rotation Speed Rusher 4 spots
RLE1Edge 60.9%Starter Speed Rusher AccelerationFinesse MovesPower MovesBlock Shedding

Designated pass rushers in the sub-package fronts. The pair aligns outside in Nickel and Dime spacing and wins with get-off, because a four-man rush has to create pressure while everyone else covers. Contain duty against scrambling quarterbacks comes with the job.

Physical 6'2 to 6'5, 245 to 270. Get-off outranks everything else.

RRE1Edge 60.9%Starter Speed Rusher AccelerationFinesse MovesPower MovesBlock Shedding

Designated pass rushers in the sub-package fronts. The pair aligns outside in Nickel and Dime spacing and wins with get-off, because a four-man rush has to create pressure while everyone else covers. Contain duty against scrambling quarterbacks comes with the job.

Physical 6'2 to 6'5, 245 to 270. Get-off outranks everything else.

REDGE1Edge 37.7%Rotation Speed Rusher Finesse MovesPower MovesAccelerationBlock Shedding

First job is winning the edge as a rusher. Aligned wide in 4-down spacing, he attacks upfield at the snap and turns speed into pressure. He sets the edge on the way to the quarterback, not instead of it.

Physical 6'3 to 6'5, 240 to 265. First step over mass.

LEDGE1Edge 36.2%Rotation Speed Rusher Finesse MovesPower MovesAccelerationBlock Shedding

First job is winning the edge as a rusher. Aligned wide in 4-down spacing, he attacks upfield at the snap and turns speed into pressure. He sets the edge on the way to the quarterback, not instead of it.

Physical 6'3 to 6'5, 240 to 265. First step over mass.

Corners Sign 4: 3 starter, 1 package Zone 4 spots
CB1Corner 95.7%Starter Zonealt: Field Corner Zone CoverageMan Coverage

Matches #1 from a zone start. He plays with zone eyes until the route distribution declares, then locks the vertical like man. Route recognition beats raw speed at this spot, which widens the recruiting pool. He midpoints #1 and #2 until the picture resolves, and the extra grass punishes slow processing more than slow legs.

Physical 5'11 to 6'2, 185 to 200. Recognition outranks timed speed.

CB1/CB2 are the outside pair; boundary vs field is alignment, the depth chart does not split them

CB2Corner 92.8%Starter Zonealt: Field Corner Zone CoverageMan Coverage

Matches #1 from a zone start. He plays with zone eyes until the route distribution declares, then locks the vertical like man. Route recognition beats raw speed at this spot, which widens the recruiting pool. He midpoints #1 and #2 until the picture resolves, and the extra grass punishes slow processing more than slow legs.

Physical 5'11 to 6'2, 185 to 200. Recognition outranks timed speed.

CB1/CB2 are the outside pair; boundary vs field is alignment, the depth chart does not split them

CB3Corner 60.9%Starter Zone Zone CoverageAwareness

Handles #2 in the match count. Seams and out-breakers from the slot are his to carry or pass off, and the pass-off decision is the skill. He funnels vertical stems to safety help and squeezes everything else.

Physical 5'9 to 6'0, 185 to 200. Processing outranks length.

first slot body; CB_slot rows cover CB3 and CB4

CB4Corner 15.9%Package Zone Zone CoverageAwareness

Handles #2 in the match count. Seams and out-breakers from the slot are his to carry or pass off, and the pass-off decision is the skill. He funnels vertical stems to safety help and squeezes everything else.

Physical 5'9 to 6'0, 185 to 200. Processing outranks length.

second slot body, on the field in dime sets

Interior DL Sign 4: 2 starter, 2 package Speed Rusher, Gap Specialist 4 spots
DT1Interior DL 98.5%Starter Speed Rusheralt: Power Rusher Finesse MovesPower MovesAccelerationBlock Shedding

Penetrates as the 3-technique. He lines up on the guard's outside shoulder and wins the B-gap with his first step, turning run downs into losses behind the line. On passing downs he supplies the interior rush that keeps quarterbacks off their spot. 26% of his snaps come from mugged formations. Protections point extra attention at the mugged threats, which leaves the nose and tackle in more one-on-one blocks they are expected to win.

Physical 6'2 to 6'5, 285 to 310. First-step quickness outranks bulk.

NT1Interior DL 89.9%Starter Gap Specialistalt: Pure Power Block SheddingStrength

Anchors the front as the shade nose. He controls the A-gap against interior runs and holds his ground against double teams so the MIKE can flow. Pocket push on late downs is a bonus on top of the run-down anchor. 29% of his snaps come from mugged formations. Protections point extra attention at the mugged threats, which leaves the nose and tackle in more one-on-one blocks they are expected to win.

Physical 6'1 to 6'4, 300 to 330. Anchor strength outranks height.

DT2Interior DL 7.2%Package Gap Specialist Block SheddingStrength

80% of snaps ask for the bear_heavy DT job, 20% ask for the odd_tite DT job. Covers the guards in bear looks and multiplies in goal line fronts, where DT3 and RDT tokens add extra interior bodies. Every rep is a single block in a phone booth, so he has to win fast with power because there is no space to recover. Plays the long end spots of the odd fronts, from a 4i on the tackle's inside shoulder in tite spacing to a head-up or outside 5-technique in base 3-4 looks. He two-gaps with length and keeps the B-gap closed so runs spill to the edge players. Rush production comes from push and hands rather than speed.

Physical 6'2 to 6'5, 300 to 330. Short-area power outranks any testing number.

In bear and heavy fronts (80% of this spot's snaps)

Archetype Gap Specialist

Physical 6'2 to 6'5, 300 to 330. Short-area power outranks any testing number.

Attributes to scout Block SheddingStrength

In odd, tite-spaced fronts (20% of this spot's snaps)

Archetype Pure Power (alt: Power Rusher)

Physical 6'3 to 6'6, 285 to 315. Arm length outranks burst.

Attributes to scout Block SheddingStrengthPower MovesFinesse Moves

DT3Interior DL 5.8%Package Gap Specialist Block SheddingStrength

Covers the guards in bear looks and multiplies in goal line fronts, where DT3 and RDT tokens add extra interior bodies. Every rep is a single block in a phone booth, so he has to win fast with power because there is no space to recover.

Physical 6'2 to 6'5, 300 to 330. Short-area power outranks any testing number.

Safeties Sign 3: 2 starter, 1 rotation Coverage Specialist, Hybrid 3 spots
FS1Safety 98.5%Starter Coverage Specialist Zone CoverageAwarenessTackle

Reads #2 from depth on his half. Match rules make him a two-way player: vertical by #2 is his to carry, anything under it frees him to rob or fit. Once his key blocks, he arrives in the run fit like an extra backer.

Physical 6'0 to 6'2, 195 to 210. Read speed outranks range.

SS1Safety 98.5%Starter Coverage Specialistalt: Hybrid Zone CoverageAwarenessTackle

Mirrors the FS job to his side. Match shells make the safeties interchangeable readers, so both need the same eyes and the same trigger. Whichever one offenses find slower becomes the target, which sets the floor for both spots.

Physical 6'0 to 6'2, 195 to 210. Read speed outranks range.

SS2Safety 30.4%Rotation Hybridalt: Box Specialist Zone CoverageAwareness

Applies when the third safety is on the field. He apexes #2 as the overhang in three-safety match looks, walling inside releases and expanding late to the flat. The wall matters most, because seams behind a soft apex break match rules. 14% of his snaps come from three_high formations, where the deep-third variant applies. In these alignments SS2 plays a true deep third, so the ask shifts from overhang force to top-down coverage: stay over #2 and #3 verticals and arrive late against the run.

Physical 5'11 to 6'2, 195 to 215. Two-plane movement outranks size.

third safety; on the field in 4-2-5 3 High, 4-2-5 Even, 4-2-5 Over G, 4-2-5 Under

Sub LBs Sign 2: 2 starter Lurker 2 spots
SUBLB1Sub LB 91.3%Starter Lurker Man CoverageZone CoverageAccelerationHit Power

Holds the second level of the sub packages that carry most snaps. The job is coverage first, matching backs and tight ends underneath, with a late rush added when the assignment stays in to block. Sub fronts field both SUBLB tokens together, so this is a sign-two position. Coverage demand runs highest here: nearly three quarters of shell-match snaps are sub personnel. 29% of his snaps come from mugged formations. Walked into an A-gap before the snap, he either arrives with the rush or bails into coverage after showing it, and the bail is the hard part. Short-area burst plus coverage recovery is the trait pair that survives the assignment.

Physical 6'0 to 6'3, 220 to 240. Coverage movement outranks bulk.

No blitz attribute exists on the scouting panel. Blitz maps to Acceleration and Hit Power here.

SUBLB2Sub LB 84.1%Starter Lurker Man CoverageZone CoverageAccelerationHit Power

Holds the second level of the sub packages that carry most snaps. The job is coverage first, matching backs and tight ends underneath, with a late rush added when the assignment stays in to block. Sub fronts field both SUBLB tokens together, so this is a sign-two position. Coverage demand runs highest here: nearly three quarters of shell-match snaps are sub personnel. 31% of his snaps come from mugged formations. Walked into an A-gap before the snap, he either arrives with the rush or bails into coverage after showing it, and the bail is the hard part. Short-area burst plus coverage recovery is the trait pair that survives the assignment.

Physical 6'0 to 6'3, 220 to 240. Coverage movement outranks bulk.

No blitz attribute exists on the scouting panel. Blitz maps to Acceleration and Hit Power here.

Off-ball LBs Sign 2: 2 package Thumper 2 spots
MIKE1Off-ball LB 7.2%Package Thumper Man CoverageZone CoverageTackleHit Power

80% of snaps ask for the bear_heavy MIKE job, 20% ask for the odd_tite MIKE job. Hits lead blockers behind a loaded line. The front eats the linemen and he meets fullbacks and pullers in the hole, keeping his fits square in short yardage. Coverage asks are minimal here. Runs free behind the trio. The front's job is to keep him unblocked, and his job is to make that matter, flowing tackle to tackle and finishing in the open field. On pass downs he owns the middle hook and carries #3 up the seam when the call asks. When it stays on the field the backers become the underneath matchers, taking final #3 and holding the middle hook against layered routes.

Physical 6'0 to 6'3, 240 to 260. Thump outranks range.

In bear and heavy fronts (80% of this spot's snaps)

Archetype Thumper

Physical 6'0 to 6'3, 240 to 260. Thump outranks range.

Attributes to scout TackleHit Power

In odd, tite-spaced fronts (20% of this spot's snaps)

Archetype Signal Caller (alt: Thumper)

Physical 6'0 to 6'3, 235 to 255. Diagnose-and-go outranks size.

Attributes to scout TacklePursuitZone CoveragePlay Recognition

WILL1Off-ball LB 7.2%Package Thumper Man CoverageZone CoverageTackleHit Power

80% of snaps ask for the bear_heavy WILL job, 20% ask for the odd_tite WILL job. Fits downhill from the weak side of heavy fronts. He fills fast and takes on climb blocks without giving ground to finish runs at the line. Backside screens are the only pass work that finds him. Scrapes behind a front built to keep him clean. He presses the line when the trio holds and falls back over the top when it slants, and his tackles come at full speed in pursuit. Flat and hook drops fill the pass downs. When it stays on the field the backers become the underneath matchers, taking final #3 and holding the middle hook against layered routes.

Physical 6'0 to 6'3, 235 to 255. Thump outranks range.

In bear and heavy fronts (80% of this spot's snaps)

Archetype Thumper

Physical 6'0 to 6'3, 235 to 255. Thump outranks range.

Attributes to scout TackleHit Power

In odd, tite-spaced fronts (20% of this spot's snaps)

Archetype Signal Caller (alt: Lurker)

Physical 6'0 to 6'2, 225 to 245. Closing speed outranks size.

Attributes to scout SpeedPursuit

Open a row for the full job and the notes behind it. The text is on the page either way, so find-in-page still works.

Below the cutoff

RDT1, 6 snaps (2.9%), ignore tier per schema thresholds.

SAM1, 3 snaps (1.45%), ignore tier per schema thresholds.

Prevent 3 Deep: 3 plays could not be mapped to a formation, so they sit outside the counts.

Built from 204 charted plays of 207 in the book. The football is verified against named coaching sources, and the attribute targets are verified against the in-game scouting screens.

Keep reading

See where 4-2-5 Shell ranks for the concepts you actually call in the CFB 27 Playbook Finder.

Coverage chalk talk that matches this style: how to run Quarters, how to run Palms and every match coverage term.