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Explaining NC State Run Fits

NC State has a great run defense. It has had such a thing now for a number of years, something that's a product of great scouting and individual player development more than anything else. State plays a style of defensive front that's very in vogue, and it doesn't necessarily do anything brilliant or inventive with its run defense, it's just really good at what it does. Here, we're going to look what that style of front allows for and some specifics regarding how State fits the fun. First, some background.

What is a run fit? 

A run fit is a gap responsibility for a specific player on the defense. Run defense is built on gap integrity. Gaps are the spaces between blockers, which are typically linemen, tight ends, h-backs or sniffers, etc. A good run defense maintains gap integrity first and foremost. There are lots of ways to do this, and we'll get into how State does it here.


Understanding run fits requires an understanding of the gap lettering system. It's pretty easy. the A gap is between guard and center. The B gap is between guard and tackle. The C gap is outside the tackle or between the tackle and tight end. The D gap is outside the tight end or between the tight end and a second tight end, and so on.

Barring some sort of bizarre formation with the line, every play will have an A, B, and C gap on both the front side and the back side before the snap.

One gap versus two gap 

Most defenses are one-gap or two-gap defenses (There is a gap-and-a-half concept pioneered in the NFL, but we won't cover that here). NC State is a one-gap defense. One-gap coverages are exactly what they sound like. Every player in the run fit is responsible for a single gap. In the 3-3 front, this would mean that the run fit would include three linemen and three linebackers against 10 personnel (no tight ends, one back) 

Two-gap defenses have become popular with the three-man fronts. In a two-gap defense, the linemen are essentially responsible for a player instead of a gap, and their job is to control their player and be able to play both gaps. This turns the linebackers into free hitters, able to scrape more and do more reading and reacting. Teams can also mix two-gap and one-gap systems. Some teams will two-gap the A gaps with the nose tackle and single-gap everything else. It sometimes looks like NC State does this because of how they play the nose tackle, and we’ll talk about that in a minute, but the Pack is one-gap all the way. 

Basic NC State run fits

Let’s take a look at State’s 3-3 at its most basic run fit. This is against a 10 personnel set from Louisville, meaning one back and no tight ends. Five linemen and no tight ends means six gaps. The Pack is in a tite front, which means the nose tackle is head up on the center and the defensive ends are shaded to the inside shoulder of the offensive tackles.

Will linebacker (#11 Payton Wilson (off-screen))

  • Weak side C gap

Mike linebacker (#26 Devon Betty)

  •  Front side A gap (note front side and strong side are not the same) 

Sam linebacker (#2 Jaylon Scott)

  • Strong side C gap

Weakside DE (#1 Davin Vann)

  • Weak side B gap

Nose tackle (#5 CJ Clark) 

  • Back side A gap 

Strong side DE (#9 Savion Jackson)

  • Strong side B gap 

This is State at its most basic. The outside linebackers set the edge in the C gaps, the defensive ends create penetration in the B gaps, the nose tackle lags to the back side A gap, and the mike linebacker covers the front side A gap. One of the big wins with this type of front is that it allows you to fit the B gaps with linemen. In a four-down front, you're often fitting the B gaps with linebackers, and that linebacker movement became a critical component of a lot of deadly RPO concepts for the offense. There is one interior run fit for a linebacker here. State is able to keep its athletes on the edge more.

We mentioned above that it sometimes looks like State two-gaps its nose tackle. A lag technique can sometimes look like this. The nose tackle’s job is to control the body of the center and work his own body into whichever A gap becomes the back side A gap. That is determined by the first step of the center. The mike linebacker then becomes responsible for the other A gap. The A gaps are distinct in this type of coverage because in many cases, the responsibilities are not determined until after the snap.

Here is an example of CJ Clark playing a lag technique. Watch number 5 try to control the back side shoulder of the center and work himself into the back side A gap. Number 10 (Caden Fordham) also reads the first step of the center and then plays to the front side A gap.

Clark and Cleveland were both pretty good at this. The Pack, of course, did not lack variety up front. They would slant the nose tackle at times, mostly in short yardage, and would in certain situations play to the front side A gap in what’s called a push technique. The lag was the most common nose tackle technique though. 

Now, many run schemes obviously utilize tight ends. What happens when there are more gaps? First, we’ll look at 11 personnel (1 RB 1 TE), then we’ll look at Notre Dame’s 157 personnel (1 RB 57 TEs). 

State is primarily a MOFC (middle-of-the-field closed) team, which means it usually has a safety in the middle of the field as a cover 1 and cover 3 heavy defense. This often brings the other safety into the box, and he is usually the first guy responsible for an additional gap.

Here’s Louisville’s 11 personnel. It’s a pretty common tite front from State with the mike in the middle and the other two backers at the apex. You can also see Sean Brown in the box, where he played a lot. This ends up

being a pass play, but Brown is likely responsible for the C gap with Wilson setting the edge in the D gap. 

Brown played a lot in the box last year, just as Ingle did the years prior. Brown is a linebacker now, but whoever wins the most reps at strong safety will take this role on again. Part of the system is having a strong safety that's physical and good in the box. For example, if Louisville ran a GT counter play toward the tight end, Brown would have to meet a pulling tackle at the point of attack.

Now here’s the mess with Notre Dame. The Irish love their tight ends, and it creates a lot of gaps to fit.

There are 10 gaps to fit here. Every player on State's defense is involved in the run fit except Devan Boykin, who is the safety in the middle of the field. This ended up being a counter play so it's hard to know for sure, but the original responsibilities were most likely something like this (again, the NT fit is determined post-snap).

Pullers vs non-pullers

Pulling linemen change the run fit for obvious reasons. After reading their keys, the first thing a linebacker will do if they read run is ID pullers. Moving linemen mean moving gaps, which mean moving run fits, and the gap responsibilities have to shift to match them. This is something that State was really good at. One of best things about the defensive front was how quickly the linebackers would trigger. They would get to their spots in a hurry against the run, and it would make gap scheme stuff difficult. Power, counter, dart, pin and pull, and G lead are all examples of plays that have moving gaps, and they're all examples of plays that had a pretty low success rate against the Wolfpack.

So why doesn’t the player with the original gap responsibility just fit the same gap? Well, for starters, defensive linemen will not be swapping gaps based on a puller read. Only the linebackers and run support will adjust to shifting gaps, and any linebacker on the back side is going to be inefficient if he has to get all the way to the front side. So instead, defenses ask their linebackers and other support players to shift one or two "non-linemen gaps" over depending on how many gaps are moving. Let’s take a look at one good example and one bad example. 

This is Clemson’s GT counter play from 10 personnel, which State clogs up easily. These are the original run fits. 50 and 74 for Clemson are going to pull, and the fits will change accordingly.

When the guard and the tackle pull, the linebackers (and any other box players) have to read this and get to their new gaps. Here is how those responsibilities shake out. 

Jaylon Scott

  • Original: Set edge in C gap 

  • After pull: Set edge in E gap and squeeze play by minimizing space created by kick out

Devon Betty

  • Original: Fit A gap nose tackle does not fit

  • After pull: Get to the point of attack, get outside of the second puller, and win the D gap

Payton Wilson

  • Original: Set edge in C gap

  • After pull: Scrape across toward frontside C gap, but don’t overplay in order to protect against cutbacks 

Here's the full play now

Devon Betty and Jaylon Scott were definitely not Drake Thomas and Isaiah Moore, but this was one area I thought both thrived, and I think Betty is a little undervalued as a linebacker heading into this year because of a lack of highlight reel plays. He was really good at reading and reacting to this stuff, especially in the back half of the season.

Now as promised, the bad example. Notre Dame pulled out a lot of gap scheme concepts last season against State. The Irish had basically two successful run plays, but one was the long touchdown following the rain delay. This was a power play that State didn’t flow to correctly, and the result was an 80-yard touchdown.

This play actually only features one puller, with the H executing his kick out from the front side. Using the same exchange rules, Scott should be setting the edge outside the kick out block and Betty should be outside the pulling guard squeezing the play. Both are in the right spot, although Betty gets chucked a bit. Payton Wilson should be inside of the pulling guard and Shyheim Battle should be crossing the formation to the gap that Wilson is in. Wilson is in the wrong gap and Battle is very slow to flow, leaving him out of position to rally to the ball.

State didn't read the puller here. That's what it looks like when things go sideways. A lack of assignment discipline was what got State in this game and the reason for its explosive play problem early in the year. It largely remedied this in the back half of the year, which is a credit to the staff and players.

Stunts and twists 

The A gap stunt

State leaned on some fun games to create penetration and blow up run plays. It had a lot of stunts and loops, one of its favorites being swapping linebacker fits. State would send Payton Wilson to the A gap and whomever was at the mike to the C gap to try and create A gap penetration. It did this a lot.

Here is an example of it against UConn in video form.

UConn busted off a long touchdown that a lot of people blamed Devon Betty for. At first glance, it looks like he overplayed the play, but in reality, State is executing this stunt. This play was not on him. Watch Wilson come from outside the tackle (the apex) to the A gap while Betty hauls butt to the edge. It's the same thing as above.

The gap integrity failure actually starts with Davin Vann, who gets reach blocked very easily, an uncharacteristic play for him.

The scrape exchange

State used a technique sometimes called a scrape exchange to create an aggressive backside pursuit without getting burned by the read option. This wrinkle involved the original C gap defender on the back side pursuing the ball aggressively while the A gap linebacker would fill the C gap, set the edge, and cover the QB pull. The job of the original C gap defender was to pursue and cut the off the A gap underneath.

Here is an example from the Duke game. Here are the original fits (assuming a lag technique from the nose tackle and a play toward the tight end).

Here is after the snap. Note where Brown and Wilson are.

Wilson executes what's called a loop to become the edge player while Brown pursues up the line. This is designed to give the QB a pull read in the read option via Brown crashing the ball, and then put Payton Wilson in his way when he pulls the ball. You'll note here that this is one of the times you'll see a push technique from the nose tackle, as State wants to squeeze the front side gaps as much as possible while it leaves B temporarily unattended. You'll also note that Devon Betty at the mike is playing over the top of his gap more so he can fall back toward B if needed.

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