Wide Receiver Positions: X, Z and Slot Receivers Explained
The wide receiver positions in the NFL are the X, the Z and the slot. What each one is asked to do, why one stands on the line, and who covers them.
By CricketTaken EditorialPublished Updated NFL Positions & Schemes22 min read
- Players required on the line (NFL)
- 7
- Defender's contact zone
- 5 yards
- Offensive pass interference
- 10 yards
- Illegal crackback block
- 15 yards
Just before the snap of nearly every NFL play, the widest receiver on each side of the field does something small and deliberate. One plants his front foot on the line of scrimmage. The other stops a yard short of it and, often, jabs a finger at the official on the sideline to make sure the difference has been noticed. That yard is where the wide receiver positions come from.
There are three of them. The X, or split end, stands on the line, usually alone on the side away from the tight end. The Z, or flanker, stands off the line, usually outside the tight end. The slot receiver lines up inside, in the space between an outside receiver and the offensive tackle. None of those names appears in the Official Playing Rules of the National Football League, which speak only of players on the line and players in the backfield. Coaches supplied the letters. The job attached to each letter follows from where the rules let that man stand and what a defense is allowed to do to him there.
The three wide receiver positions and the job each one is given
A standard NFL offense puts three wide receivers on the field with one tight end and one running back. Two of the receivers are outside, near the painted numbers. The third is inside one of them.
| Position | Older name | Where he lines up | On the line? | The job in one line |
|---|---|---|---|---|
| X | Split end | Wide, usually away from the tight end | Yes | Beat a cornerback one-on-one with no help from the formation |
| Z | Flanker | Wide, usually on the tight end's side | No | Move before the snap, run deep and across the field |
| Slot | Slot back, inside receiver | Between the tackle and an outside receiver | Usually not | Work the middle, read the coverage, block on runs |
| Y | Tight end | Attached, next to an offensive tackle | Yes | Block like a lineman, then run routes |
The Y is in the table because the lettering makes no sense without him. He is not a wide receiver, and our guide to what a tight end does covers his half of the story.
Each of the three wideout spots asks for something different. The X has to win a physical fight in the first two steps, because a cornerback can stand in his face and nobody is nearby to help. The Z gets a running start, sometimes literally, and is the man offenses send on the long developing routes. The slot receiver plays in the most crowded part of the field and is paid for decisions as much as for speed: on many of his routes he does not know which way he will break until he has seen what the defender does.
Height, weight and forty-yard times tend to sort players toward one spot or another. They do not bind anyone. A coach who has a 6-foot-4 receiver with a slot man's feet will put him in the slot, and has.
On the line or off it: the seven-man rule behind the X and the Z
Start with the exception. A tight end who has a wide receiver standing on the line outside him is not allowed to catch a forward pass.
That is the rule everything else hangs on. Rule 7 of the NFL rulebook, in its section on the position of players at the snap, requires the offense to have at least seven players on the line of scrimmage. Five of them are the interior linemen, who wear numbers 50 through 79 and are ineligible. That leaves two. Of the players on the line, only the man at each end is an eligible receiver. Everyone standing in the backfield, at least a yard behind the line, is eligible too.
Put a tight end next to the right tackle and he is the end man on that side: eligible. Now place a receiver on the line outside him and the tight end is "covered up." He has become an interior lineman in the eyes of the officials, wearing an eligible number in an ineligible spot, and if he runs a route the offense is penalized. So the receiver on the tight end's side backs up a yard. He is the flanker, the Z. On the other side, where there is no tight end, somebody has to be the seventh man on the line, and that is the split end, the X.
- 7Players required on the line
- 4Players left for the backfield
- 1Players who may be moving at the snap
- 1Seconds a shifted player must be set
Figures from the NFL rulebook's formation, shift and motion rules. The NCAA writes its formation rule differently, capping the backfield at four players rather than requiring seven on the line.
The college rule reaches almost the same place by a different road. The NCAA Football Rules Book says no more than four players may be in the backfield and at least five numbered 50 through 79 must be on the line, which means a team that sends out only ten men by mistake is not automatically in an illegal formation. In the NFL the count is of the line itself.
Why receivers point at the sideline official
The officials who judge all this are the down judge and the line judge, who stand on opposite sidelines looking straight down the line of scrimmage. A receiver split 20 yards from the ball cannot easily tell whether his helmet has broken the plane through the center's waistline, which is the rulebook's test for being on the line. The official can.
So the receiver points, or looks, and the official answers. The common mechanic is an arm held out toward the offensive backfield, which tells the nearest receiver he is being counted as off the line. No arm means he is on it. Receivers who are meant to be off the line check because a second man on the line outside them would cover them up; receivers meant to be on it check because an offense with only six on the line has committed a foul before the play starts. Our page on the NFL illegal formation penalty goes through what the flag costs and how officials warn a player before throwing it.
The X receiver: alone on the weak side against press coverage
The side of the formation with the tight end is the strong side. The X usually lives on the other one, and he is often the only eligible receiver over there.
Being on the line has two consequences. He cannot be in motion when the ball is snapped, since the NFL allows that only to a player who is lined up in the backfield. And there is no cushion between him and the cornerback. A defender may legally contact a receiver within five yards of the line of scrimmage, and a corner in press coverage uses every inch of that allowance, punching at the receiver's chest plate as he comes off the ball to delay the route and knock its timing out.
The X has to beat that jam from a standing start, with the sideline squeezing him on one side and no teammate close enough to run a defender off him. It is the hardest release in the offense. Coaches have traditionally put their biggest and strongest receiver there for exactly that reason: long arms to swat a corner's hands away, enough mass that a punch does not move him, and the leaping ability to win a ball thrown up along the boundary when he has not gotten clean separation. Calvin Johnson, listed by the Detroit Lions at 6-foot-5, was close to the template.
There is a schematic reason offenses like a dominant X as well. When three receivers line up to one side, the X is left by himself on the back side, and the defense has to declare what it thinks of him. Leave one cornerback over there with no safety help and the quarterback has an easy decision. Roll a safety toward the X and the three receivers on the far side are working against fewer defenders than the play was drawn up for. A receiver who commands that extra attention has helped the offense before he runs a step.
The Z receiver: a free release and the freedom to go in motion
The Z's yard of depth buys him time. A cornerback who wants to press him has to cross the line of scrimmage to do it, which he cannot, so the first contact comes after the receiver is already moving and has already chosen a side. Defensive backs still press flankers. It is simply harder to land a clean shot on a target who has a step to work with.
The larger gift is motion. Because the Z is a back under the rules, he is the receiver an offense can send across the formation before the snap, provided he is moving parallel to the line or away from it when the ball is snapped and he is the only one doing so. Motion does several things at once. It can change the strength of the formation and force linebackers to reset. It can get the Z a running start on a crossing route or a jet sweep. And it makes the defense talk, which is the subject of a later section. The limits on all this, including the one-second pause required after a shift, are set out in our comparison of the illegal shift and illegal motion fouls.
Routes follow from the alignment. The Z tends to run the patterns that take time and space to develop:
- the deep post and the go route, where a free release turns into a stride of separation 30 yards downfield
- the deep over, a crossing route that climbs to 18 or 20 yards and travels the width of the field
- the dig, breaking in behind the linebackers
- shallow crossers out of short motion, with the receiver already near full speed at the snap
Jerry Rice played flanker for most of his years in San Francisco, which is one reason so many of his catches came on in-breaking routes he took at full stride with a defender trailing. The position suited a receiver whose gift was timing rather than raw size.
Speed is the usual requirement. Not always sprinter's speed, but the Z is typically the faster of the two outside receivers and the one the defense has to honor deep.
The slot receiver: the two-way go over the middle
An outside receiver has the sideline as a wall. He can release inside or he can run in a narrow corridor along the boundary, and the cornerback knows it. The slot receiver has grass on both sides. Coaches call it the two-way go, and it is the reason the slot is so hard to cover man-to-man: the defender cannot use the sideline as help and has to guess, or wait.
Offenses lean on that with option routes. The receiver runs to a depth, often five or six yards, reads the leverage of the man over him, and breaks away from it. In against an outside-shaded defender, out against an inside one, and a sit-down in the open grass if the coverage turns out to be zone. The quarterback is reading the same defender and has to reach the same conclusion at the same instant. When it works the throw looks effortless. When the two disagree, the ball goes to nobody, and the broadcast shows a quarterback with his palms up.
Quickness over top speed
Wes Welker caught at least 100 passes in five different seasons for the New England Patriots between 2007 and 2012, nearly all of them from the slot, and he was listed at 5-foot-9. He was not especially fast in a straight line. What he had was the ability to stop and restart in less space than the defender needed. That is the trait the position rewards: short-area quickness, a low center of gravity, and no fear of the linebackers and safeties who patrol the middle.
The opposite body type works too. A tall, heavy receiver in the slot, the "big slot," gets matched against a smaller nickel back or a slower linebacker and wins with size instead. Larry Fitzgerald spent the back half of his career with the Arizona Cardinals largely in that role.
The run blocking the spot demands
The slot man lines up closer to the ball than any other wide receiver, so he is in the middle of the running game whether he likes it or not. He is asked to block the nickel back, to dig out a safety walking down toward the line, and on some plays to crack down on a linebacker who outweighs him by 40 pounds. A slot receiver who will not block tells the defense what the play is the moment he trots onto the field. Coaches notice. So do defensive coordinators.
Why Y is the tight end, and how the lettering runs to F, H and beyond
The letters come from the diagrams. When the pro set became the standard formation, with two backs behind the quarterback, a split end to one side and a tight end and flanker to the other, playbooks needed a short way to tag the three receivers in a play drawing. X, Y and Z did it, and Y fell to the tight end. A coach could then write a play as a list of assignments by letter, and it would hold no matter who was in the game.
Once offenses put a third wide receiver on the field in place of the fullback, they needed a fourth letter. That is where agreement ends. Many systems call the slot receiver F, a holdover from the fullback he replaced. Others call him H, the same letter some staffs give to a tight end who moves around the formation. A second tight end is often U. Some playbooks use A and B. A few number their receivers instead.
None of this is governed by anything. The letters are bookkeeping, and a receiver who changes teams has to relearn which one he is. What stays put across nearly every NFL and college playbook is the core of it: X is on the line, Z is off it, Y is the tight end.
A consequence worth knowing when listening to a broadcast is that an announcer who says "he's their X" is describing an alignment and a set of responsibilities. He is saying nothing about whether that player is the team's best receiver.
Getting open: releases, stems, breaks and stacking a defender
Straight-line speed gets a receiver drafted. It does not get him open against an NFL cornerback, who is nearly as fast and gets to run backward with a head start. Separation is manufactured, in four stages.
- ReleaseAgainst press, the receiver uses his feet to move the cornerback and his hands to clear the jam, then gets vertical as fast as he can.
- StemHe runs the first part of every route at the same speed and on the same path, so a go, a comeback and a dig look identical for ten yards.
- BreakHe drops his weight, plants and changes direction in as few steps as possible. Wasted steps here are how defenders recover.
- StackOnce past the defender on a deep route, he moves directly in front of him, so the defender cannot see the ball and cannot reach it without fouling.
A description of standard receiver technique as coaches teach it; the exact footwork and terms differ from one position coach to another.
The release is a fight. A receiver might take a hard jab step inside to turn the corner's hips and then swim an arm over his outside shoulder, or simply chop the defender's hands down and run through the space. The best releasers have three or four of these and choose based on where the corner puts his weight.
The stem is a lie told with the whole body. Every route in the playbook is meant to look like a deep route for as long as possible, because a defensive back who believes he is about to be run past will keep retreating. The catalogue of patterns that grow out of those identical first steps is laid out in our guide to the route tree and its nine numbered routes.
The break is where route runners separate themselves from sprinters. A fast receiver who needs five choppy steps to slow down for a comeback has told the cornerback what is coming. One who can sink his hips and come out of the cut in two has two yards of room, which at this level is wide open.
And stacking is the quiet finish to a deep route. A receiver who has beaten his man by half a step and stays beside him is still covered. One who slides in front has taken the defender's path to the ball away from him entirely.
Role labels against alignment labels: why a number one receiver can line up anywhere
Football uses two vocabularies for wide receivers and tends to mix them up in the same sentence.
| Label | What it describes | Does it tell you where he lines up? |
|---|---|---|
| X, Z, slot | An alignment and the assignments that go with it | Yes |
| Possession receiver | A style: short and intermediate routes, reliable hands, first downs | No |
| Deep threat | A style: vertical speed that forces a safety to stay back | No |
| Gadget player | A usage: jet sweeps, screens, reverses, the occasional throw | No |
| Number one receiver | A ranking: the player the passing game runs through | No |
A possession receiver is the man the quarterback looks for on third-and-6, and he can be an X, a Z or a slot. A deep threat stretches the field from wherever he lines up. A gadget player may barely run conventional routes at all, getting the ball on plays designed to put it in his hands behind the line.
The depth-chart shorthand of WR1, WR2 and WR3 is a ranking and nothing else. Modern offenses work hard to keep their best receiver from being the X on every snap, because a defense that knows where he will be can plan for him: press him with its best cornerback, tilt a safety over the top, and live with the consequences elsewhere. Move him into the slot on one play, put him in motion as the Z on the next, hide him as the inside man in a bunch on the third, and the defense has to find him and adjust every time.
The best receivers of the last decade have been the ones who could play all three spots. The alignment letters describe a play. They no longer describe a career.
How formations move receivers around: trips, bunch, stack and motion
Formation is the offense's first move, and a good deal of it is aimed at getting a receiver away from the defender or the technique the defense would prefer. The full catalogue is in our guide to offensive formations. Four ideas matter most for receivers.
Trips. Three receivers to one side, one to the other. The lone man on the back side is nearly always on the line, so whoever stands there is the X for that play.
Bunch. Three receivers packed within a couple of yards of each other, close to the tackle. One is on the line at the point and the other two are off it. From that cluster they cross paths on the release, and defenders in man coverage have to pick their way through traffic. Press is almost impossible against a bunch, because only the point man can be reached.
Stack. Two receivers, one directly behind the other. The front man is on the line and the back man gets a free release in either direction. It is the cheapest way there is to get a jam off a receiver who struggles with one.
Motion. A receiver who starts outside and motions in can arrive in the slot at the snap, and a slot man can motion out wide. The defender assigned to him has to travel or hand him off.
One limit applies to all the crossing and rubbing. In the NFL, an offensive player who blocks a defender more than one yard beyond the line of scrimmage before the ball is thrown has committed offensive pass interference, a 10-yard penalty. A receiver may run his route and let a defender collide with a teammate's path; he may not set a screen. The line between the two is thin and is officiated by judgment, as our explainer on how pass interference is called sets out.
How many wide receivers are available to move around depends on who was sent into the huddle, which coaches describe with a two-digit code covered in our guide to personnel groupings.
Who covers whom: outside cornerbacks, the nickel back and what the matchup reveals
Two cornerbacks start on the outside receivers. When a third wideout comes on, the defense answers by taking off a linebacker and bringing in a fifth defensive back, the nickel, who covers the slot. That substitution has become so routine that the nickel plays more snaps than the third linebacker on most NFL teams, a shift traced in our piece on nickel and dime defense.
Covering the slot is its own trade. The nickel back has no sideline to lean on, has to tackle running backs who cut into his gap, and is frequently sent on blitzes because he starts so near the ball. He is a different player from the long outside cornerback, in roughly the way a slot receiver is a different player from an X.
Quarterbacks study how the defense lines up against the receivers because it leaks information.
- A cornerback who follows one receiver from side to side, wherever he aligns, signals man coverage on that player at least.
- Cornerbacks who stay on their own sides regardless of who lines up there suggest zone, or a defense that does not match by player.
- A defender who runs across the formation with a receiver in motion is in man. If instead the defenders pass the receiver along and bump over a spot, it is zone.
- A cornerback lined up over a tight end while a linebacker walks out over a wideout is usually a zone tell, because nobody would choose that matchup man-to-man.
Defenses know they are being read and disguise accordingly, showing one thing and rotating to another at the snap. The underlying choice, and what each side of it gives up, is the subject of our explainer on man and zone coverage.
Receivers as blockers: the stalk block, the crack block and the crackback rules
A long run nearly always has a wide receiver's block somewhere in it. The running back gets through the line on the work of the men up front. He gets from 12 yards to 50 because a receiver kept a cornerback occupied.
The stalk block is the standard one. The receiver releases as if running a route, driving the cornerback backward. When the defender recognizes the run and comes forward, the receiver breaks down in front of him, gets his hands inside on the chest, and mirrors him. He does not have to flatten anyone. He has to stay between the defender and the ball for three seconds.
The crack block is more violent. The receiver comes down the line toward the ball and blocks a linebacker or safety who is watching the backfield, sealing him inside so the run can get to the edge. The cornerback who was covering that receiver now has to replace the man who was blocked, which is a job few cornerbacks enjoy.
Because the defender on the end of a crack block often never sees it coming, the rulebook hems it in.
Under the NFL's illegal crackback rule, a player who lines up more than two yards outside the offensive tackle and then comes back toward the ball may not block a defender below the waist within five yards of the line of scrimmage, and may not hit him in the head or neck area. The contact has to land between the shoulders and the waist. A separate rule adopted in 2019 made the blindside block a foul across the field: a player moving toward or parallel to his own end line may not deliver forcible contact with his helmet, shoulder or forearm. Both are 15 yards.
The effect has been to change how the crack is taught. Receivers are now coached to get their head across the front of the defender and to shield him with their hands rather than launch a shoulder into his ribs. The college rulebook has its own versions of the blindside and low-block restrictions, written differently, and the two should not be assumed to match on any given play.
From ends to wideouts: how the split end and the flanker grew out of the T-formation
There were no wide receivers in the T-formation. There were two ends, each lined up tight to a tackle, and three backs in a row behind the quarterback. The ends blocked on most plays and went out for passes on some.
The first step was to move an end away from the tackle. Don Hutson of the Green Bay Packers, who played from 1935 to 1945, is the player most associated with it: he lined up split from the formation often enough, and caught enough passes when he did, that the "split end" became a recognizable thing. He retired with 99 touchdown receptions, a total nobody passed until 1989.
The second step was to take a halfback out of the backfield and stand him out wide on the other side. The Los Angeles Rams did this with Elroy Hirsch around 1950, and he is usually named as the first flanker, though historians who have gone back through the film argue about how often he actually lined up there. The results are not in dispute. In 1951 Hirsch caught 66 passes for 1,495 yards and 17 touchdowns in a 12-game season.
By the 1960s the arrangement had hardened into the pro set: a split end, a tight end, a flanker and two running backs. That is the formation the X, Y and Z letters were drawn for.
The third receiver took longer. Rule changes in 1978 limited defenders to contact within five yards of the line and loosened the restrictions on pass blocking, and the passing game expanded to fill the space. Offenses began replacing the fullback with another wideout on passing downs, then on most downs. Joe Gibbs's Washington teams of the late 1980s ran much of their offense from one-back sets, and in 1989 Art Monk, Gary Clark and Ricky Sanders each finished with more than 1,000 receiving yards. Run-and-shoot teams went further and used four.
Three receivers, one tight end and one back is now the default grouping in the NFL, which is why the slot receiver is a starter in everything but name and why the nickel back is too. More of the rules, formats and history behind the game are collected on our American football hub.