It has been an ongoing discussion/debate on various threads over the past couple of seasons about which defense is better suited for Nebraska, the 3-4 Defense or the 4-3 Defense. Because the glory days of the 90s coincided with Nebraska and Charlie McBride switching to the 4-3, there is a strong affinity for that defense among Nebraska fans. Nebraska/McBride had run the 5-2/50 Base defense throughout the 80s and early 90s, and that is a variant of the 3-4, but there doesn't seem to be as much nostalgic connection to the defenses of that era. There have been spirited debates about which is more difficult to recruit: DEs for the 4-3 or OLBs for the 3-4, as well as NG for the 3-4 versus DTs for the 4-3. All of that is interesting, and I have my own opinions on all of it, but I don't think that any of us have talked about why Chinander prefers the 3-4 Defense. At the recent coaches' clinic, he talked about how his thinking evolved, and I thought it was interesting, so I thought that I'd share it here with some explanation to follow.
Chinander had been an offensive coach (TEs) when he was at Northern Iowa in the mid-2000s, but he took a step down by becoming a grad assistant at Oregon in 2010 under Chip Kelly, who had just completed his first season as head coach at Oregon. Chinander said that when Kelly took over as head coach, he told the defensive staff, "You can run whatever you want as long as it's based on a 3-man front."
Chinander said that some defensive staff members had asked, "Why not a 4-man front?"
Kelly responded, "If you come out in a 4-man front and put a D-tackle in a 3-technique, I'm going to score a hundred points on you." Kelly didn't want his defense running schemes that couldn't match up against his offense. He also wanted it to be variable enough to match up with anybody. An attacking 3-4 is what came out of that.
So what is to be made of the comment about a 4-man front with DTs in a 3-technique being so easy to exploit? It took me a couple of minutes of thinking about it to connect the dots, but I'm pretty sure that I get what Kelly and Chinander meant by that claim, and it's especially relevant to Nebraska fans now because Frost's offense is built around the same principles that involve the same basic plays. The foundation of both the Chip Kelly offense and the Scott Frost offense is the Inside Zone Read, and in its original form, it was built to tear apart a 4-3 defense. Let's take a look at how it would do that.
Here is a 2x2 Spread formation that is one of Kelly and Frost's base offensive looks. Frost usually likes his RB straight behind the QB, but both have/had variations. I’ll be using the Chip Kelly formation and RB path for all of these drawings because that was the one that was designed to attack the 4-3. Frost’s offense likes to have the RB’s aiming point for the Inside Zone to be directly at the Center after taking a step to the side to set up the mesh with the QB. The Frost Inside Zone is better at attacking a 3-4, but it would still have the same advantages against a 4-3 as the Chip Kelly Inside Zone.
If any defense doesn't have at least 2 defenders out wide to cover the WRs on either side, and/or if the DBs aren’t tight to the Line of Scrimmage, the offense would automatically run Bubble Screens until the defense was forced to shift guys over and up. Once the defense had 4 DBs committed to the outside, there would be 7 left to handle the middle and the deep portions of the field. For the purposes of understanding how the Inside Zone Read attacks a 4-3 defensive front, we no longer need to worry about the 2x2 outside receivers or the 4 DBs who are assigned to cover them. If a DB starts cheating to the inside, you go back to the Bubble Screen, and he's toast.
Did you notice that there are no deep safeties with this formation? This would be what’s called “Cover O” because there isn’t anybody back deep. There are about a kajillion ways to attack this sort of defense with a long pass, but in the end the offense will want at least 1 or 2 fast WRs to go deep after either rubbing off a defender with a teammate’s crossing route or else establishing initial position and outrunning a defender. If you have 4 WRs with speed, you can have each side do a crossing route before they all go deep, which is the 4-Verts (4 Verticals) pattern that is the heart of the Air Raid offense. Regardless of how you attack it, this is why every team wants to have at least 1 or 2 guys who are tall and can run fast to force the defense to put at least one Safety back there, which will then open up more space underneath for the offense by taking a defender out of the Box. Here’s what that looks like with a defender back deep:
The DEs would need to set the edge of the defense, so they would have to line up on the outside shoulder of the OTs. The DTs can line up anywhere inside, but with a balanced offensive formation, most defensive coaches like to have their DTs lined up on the outside shoulder of the Guards, which is what is referred to as a 3-technique. Defenses like to do this because the DT is already well positioned to stop any plays going through the B-gap (between the OT and the Guard), and if the Guard pulls, he is well positioned to follow him, pursue and blow up the play. In theory the Guards should have to block him, which means that the Center has to be agile enough to get out and block the LB one-on-one after the snap, which is hard to do.
Notice, also, that this is no longer a true 4-3 defense as there are now only 2 LBs in the Box. The defense would still have to decide where to line up the LBs. If they cheat to one side, the offense can run away from him. If they both line up too far inside, the offense can run an Outside Zone Read, and it will be very hard to get outside to cover it. If they line up too far outside, they’re out of position for the Inside Zone. Also, choice of personnel matters. If the LBs are more Inside LBs, the offense is going to make them run laterally as much as possible, regardless of where they line up. If the LBs are more Outside LBs, the offense is going to run right at them and make them take on interior linemen in tight spaces. Regardless, with only 6 defenders in the Box, the offense now has a numbers advantage with 7 offensive players. With 2 LBs stacked behind the DTs, it is probably the strongest look that the defense can give to stop the Inside Zone without giving up too much somewhere else.
Now that everybody is set up and ready to go, here’s what the blocks and running paths would look like for an Inside Zone Read:
For an Inside Zone Read, every offensive lineman steps forward at an angle towards the playside, which is to the left as that is where the RB’s path will take him. If there is a defender on the line to his left, he will block him, one-on-one. If there is a defender to his right, he will leave him to be blocked by the O-lineman who is coming up beside him. The Left OT would take the DE on his outside shoulder, and he would push him as far upfield and outside as possible until the RB has cleared his level. There should be a double-team at the point of attack whenever possible, which is why both the Center and the Left Guard would initially be blocking the DT on the defense’s right side. As soon as he is under the control of one or the other—ideally it would be the Left Guard—the extra O-lineman (in this case, the Center) climbs up to the next level to get hands on the LB who is coming towards the hole to fill. Because the Inside Zone is a straight-ahead sort of play, it’s very difficult for this LB to get around this block, so he will have to either be big enough and strong enough to stand up the Center, or else have technique that is good enough to get past the Center in tight space. Either is difficult, and keep in mind that the RB will be coming into the hole as fast as possible, so if the LB can only stick out an arm to try and stop him, the RB should be able to run through it.
On the backside of the O-line there would be another combo block as the Right Guard and Right OT would both push back on the DT until one or the other O-lineman has control over him (ideally, the OT), and the extra blocker (ideally, the RG) would climb to the next level to intercept the backside LB. If the LB is quick and is already in the hole, the RG would shove him farther to his left, opening up a wide cut-back lane for the RB as soon as he gets to the Line of Scrimmage. If the LB is slow in getting to the hole, the RG would turn his shoulders perpendicular to the Line of Scrimmage and seal him off away from the play so that the RB doesn’t have to worry about him at all. In a more routine situation, the RG would be coming off his chip block of the DT and would meet the LB 2-3 yards upfield from where the ball was snapped, and he would drive block him as far backward as possible. It would be the responsibility of the RB to cut off of the blockers.
Finally, the backside DE (circled in red) is left unblocked. The thin red line from the QB towards where the DE will be after the snap shows where the QB’s eyes should be focused. If the DE comes crashing down the line to chase the RB, the QB pulls the ball back from the RB after the RB runs past him, and then the QB runs parallel to the Line of Scrimmage until he has cleared the DE so that the QB can turn and cut upfield. By reading the backside DE, every defender is accounted for, and anybody who makes the tackle on the RB or QB would have to do so by defeating the blocker and making a play off-balance while the ball-carrier is at full speed. The extra D-lineman in the 4-man front makes it easier for the offense to do this.
Now let’s take a quick look at the whole field for a 3-4 defensive front against the same spread formation. Let’s cut away the 4 outside WRs and the 4 outside DBs again. Here’s what the Box and the area immediately around it looks like:
Again, this is a Cover 0 with no deep safeties, but because the OLBs are able line up in the Alley halfway between the OT and the inside receiver, the Safeties can back off a bit more and play deeper. If it’s an obvious passing situation, or if the team needs to throw the ball, you’d pull a LB or 2 and put in more DBs, but right now this is what a balanced 3-4 front would look like against a balanced 2x2 Spread formation. The OLBs take away any easy inside routes or passes and pursue to take away any cutbacks on a Bubble Screen. The CB and Safety are still in position to take away the screens or anything deep as long as the CBs are able to turn and run, one-on-one with the WRs that they’re covering on the outside.
Even though there are now only 5 defenders in the Box, having those OLBs hanging just outside the Box in the Alleys creates some issues. First of all, who will be the defender who has to contain the edge on either side? More often than not the DEs would attack the inside B-gap, and the OLBs would have outside contain. The NG would more often than not attack the Center directly, and he would be responsible for covering both A-gaps. How are the O-linemen going to climb up to block those LBs?
Here's what it looks like:
The first thing that you should notice is that it’s all but hopeless for the QB to keep the ball on the Read part of the play unless that backside OLB is blitzing or incredibly slow. He should still be out of the play for the RB though. Starting with the Center, he will have a tough time moving the NG, and the NG will be trained to react to the direction of the Center’s first step and attack in that direction. Because the backside Guard (the RG) would be working to combo block him, the 2nd blocker would have to push him in the direction of the play. A decent NG is going to take away the A-gap on the playside for the RB so that he has to at least run around him. Look at the angle of the path that the RG needs to take to get to the backside ILB. If the NG holds his ground reasonably well, it will be a shorter path for the backside ILB to scrape past the NG to the playside than it will be for the backside Guard to climb up to him, and it will be even harder if he tries helping the C to combo block the NG first. If the Center takes that backside LB, the RG would have to block the NG without pushing him sideways towards where the play is supposed to be aiming. The only O-lineman who would have a reasonably good angle for his block would be the Right OT blocking the backside DE, but that’s only if the OT gets his foot into that gap first to gain leverage. A quick DE could shoot past that block and be in the backfield before the RB has the ball.
As difficult as all of that is, it’s on the playside that the blockers will have the most trouble, both because of tough angles, but also because that OLB is a 3rd defender who is lurking just outside the Box. If the DE steps towards the B-gap, who blocks him? By typical zone blocking rules, the LG should take him and drive him to the left and backwards, but that would cut the Left OT off from being able to get to the playside ILB. The O-linemen would probably make a Block Call for them to combo block the DE towards the ILB, then the LG would come off the combo block to intercept the ILB before he gets into the hole. If the DE doesn’t move, or if the ILB is quick or good at fighting off blocks or both, he’s already in position to make a play on the RB. Finally, don’t forget about the playside OLB. This is where Alex Davis really struggled last year, but a decent OLB who reads the blocks should be looking into the backfield while coming across the Line of Scrimmage and squeezing down on the RB to force him towards his teammates in as tight of a space as possible. A very good OLB can make that play at or before the RB gets to the Line of Scrimmage. If you use the OT to block him, the LG has to take the playside DE, and there’s nobody left to block the playside ILB. Even if every block is made, all the D-line has to do is hold their ground, and every gap has a defender standing in it, and every defender’s momentum is taking him closer to where the ball carrier is initially going.
Whether you think the 4-3 is the greatest thing since sliced bread, or if you think that the 3-4 will be tough to find recruits, at least now you know why Nebraska is using it. Keep in mind that in this or any other system, an athlete that is far superior can make plays regardless of scheme, so it’s not as though my high school students can run this offense and beat an NFL team running a 4-3.
Comments or questions?
Chinander had been an offensive coach (TEs) when he was at Northern Iowa in the mid-2000s, but he took a step down by becoming a grad assistant at Oregon in 2010 under Chip Kelly, who had just completed his first season as head coach at Oregon. Chinander said that when Kelly took over as head coach, he told the defensive staff, "You can run whatever you want as long as it's based on a 3-man front."
Chinander said that some defensive staff members had asked, "Why not a 4-man front?"
Kelly responded, "If you come out in a 4-man front and put a D-tackle in a 3-technique, I'm going to score a hundred points on you." Kelly didn't want his defense running schemes that couldn't match up against his offense. He also wanted it to be variable enough to match up with anybody. An attacking 3-4 is what came out of that.
So what is to be made of the comment about a 4-man front with DTs in a 3-technique being so easy to exploit? It took me a couple of minutes of thinking about it to connect the dots, but I'm pretty sure that I get what Kelly and Chinander meant by that claim, and it's especially relevant to Nebraska fans now because Frost's offense is built around the same principles that involve the same basic plays. The foundation of both the Chip Kelly offense and the Scott Frost offense is the Inside Zone Read, and in its original form, it was built to tear apart a 4-3 defense. Let's take a look at how it would do that.
Here is a 2x2 Spread formation that is one of Kelly and Frost's base offensive looks. Frost usually likes his RB straight behind the QB, but both have/had variations. I’ll be using the Chip Kelly formation and RB path for all of these drawings because that was the one that was designed to attack the 4-3. Frost’s offense likes to have the RB’s aiming point for the Inside Zone to be directly at the Center after taking a step to the side to set up the mesh with the QB. The Frost Inside Zone is better at attacking a 3-4, but it would still have the same advantages against a 4-3 as the Chip Kelly Inside Zone.
If any defense doesn't have at least 2 defenders out wide to cover the WRs on either side, and/or if the DBs aren’t tight to the Line of Scrimmage, the offense would automatically run Bubble Screens until the defense was forced to shift guys over and up. Once the defense had 4 DBs committed to the outside, there would be 7 left to handle the middle and the deep portions of the field. For the purposes of understanding how the Inside Zone Read attacks a 4-3 defensive front, we no longer need to worry about the 2x2 outside receivers or the 4 DBs who are assigned to cover them. If a DB starts cheating to the inside, you go back to the Bubble Screen, and he's toast.
Did you notice that there are no deep safeties with this formation? This would be what’s called “Cover O” because there isn’t anybody back deep. There are about a kajillion ways to attack this sort of defense with a long pass, but in the end the offense will want at least 1 or 2 fast WRs to go deep after either rubbing off a defender with a teammate’s crossing route or else establishing initial position and outrunning a defender. If you have 4 WRs with speed, you can have each side do a crossing route before they all go deep, which is the 4-Verts (4 Verticals) pattern that is the heart of the Air Raid offense. Regardless of how you attack it, this is why every team wants to have at least 1 or 2 guys who are tall and can run fast to force the defense to put at least one Safety back there, which will then open up more space underneath for the offense by taking a defender out of the Box. Here’s what that looks like with a defender back deep:
The DEs would need to set the edge of the defense, so they would have to line up on the outside shoulder of the OTs. The DTs can line up anywhere inside, but with a balanced offensive formation, most defensive coaches like to have their DTs lined up on the outside shoulder of the Guards, which is what is referred to as a 3-technique. Defenses like to do this because the DT is already well positioned to stop any plays going through the B-gap (between the OT and the Guard), and if the Guard pulls, he is well positioned to follow him, pursue and blow up the play. In theory the Guards should have to block him, which means that the Center has to be agile enough to get out and block the LB one-on-one after the snap, which is hard to do.
Notice, also, that this is no longer a true 4-3 defense as there are now only 2 LBs in the Box. The defense would still have to decide where to line up the LBs. If they cheat to one side, the offense can run away from him. If they both line up too far inside, the offense can run an Outside Zone Read, and it will be very hard to get outside to cover it. If they line up too far outside, they’re out of position for the Inside Zone. Also, choice of personnel matters. If the LBs are more Inside LBs, the offense is going to make them run laterally as much as possible, regardless of where they line up. If the LBs are more Outside LBs, the offense is going to run right at them and make them take on interior linemen in tight spaces. Regardless, with only 6 defenders in the Box, the offense now has a numbers advantage with 7 offensive players. With 2 LBs stacked behind the DTs, it is probably the strongest look that the defense can give to stop the Inside Zone without giving up too much somewhere else.
Now that everybody is set up and ready to go, here’s what the blocks and running paths would look like for an Inside Zone Read:
For an Inside Zone Read, every offensive lineman steps forward at an angle towards the playside, which is to the left as that is where the RB’s path will take him. If there is a defender on the line to his left, he will block him, one-on-one. If there is a defender to his right, he will leave him to be blocked by the O-lineman who is coming up beside him. The Left OT would take the DE on his outside shoulder, and he would push him as far upfield and outside as possible until the RB has cleared his level. There should be a double-team at the point of attack whenever possible, which is why both the Center and the Left Guard would initially be blocking the DT on the defense’s right side. As soon as he is under the control of one or the other—ideally it would be the Left Guard—the extra O-lineman (in this case, the Center) climbs up to the next level to get hands on the LB who is coming towards the hole to fill. Because the Inside Zone is a straight-ahead sort of play, it’s very difficult for this LB to get around this block, so he will have to either be big enough and strong enough to stand up the Center, or else have technique that is good enough to get past the Center in tight space. Either is difficult, and keep in mind that the RB will be coming into the hole as fast as possible, so if the LB can only stick out an arm to try and stop him, the RB should be able to run through it.
On the backside of the O-line there would be another combo block as the Right Guard and Right OT would both push back on the DT until one or the other O-lineman has control over him (ideally, the OT), and the extra blocker (ideally, the RG) would climb to the next level to intercept the backside LB. If the LB is quick and is already in the hole, the RG would shove him farther to his left, opening up a wide cut-back lane for the RB as soon as he gets to the Line of Scrimmage. If the LB is slow in getting to the hole, the RG would turn his shoulders perpendicular to the Line of Scrimmage and seal him off away from the play so that the RB doesn’t have to worry about him at all. In a more routine situation, the RG would be coming off his chip block of the DT and would meet the LB 2-3 yards upfield from where the ball was snapped, and he would drive block him as far backward as possible. It would be the responsibility of the RB to cut off of the blockers.
Finally, the backside DE (circled in red) is left unblocked. The thin red line from the QB towards where the DE will be after the snap shows where the QB’s eyes should be focused. If the DE comes crashing down the line to chase the RB, the QB pulls the ball back from the RB after the RB runs past him, and then the QB runs parallel to the Line of Scrimmage until he has cleared the DE so that the QB can turn and cut upfield. By reading the backside DE, every defender is accounted for, and anybody who makes the tackle on the RB or QB would have to do so by defeating the blocker and making a play off-balance while the ball-carrier is at full speed. The extra D-lineman in the 4-man front makes it easier for the offense to do this.
Now let’s take a quick look at the whole field for a 3-4 defensive front against the same spread formation. Let’s cut away the 4 outside WRs and the 4 outside DBs again. Here’s what the Box and the area immediately around it looks like:
Again, this is a Cover 0 with no deep safeties, but because the OLBs are able line up in the Alley halfway between the OT and the inside receiver, the Safeties can back off a bit more and play deeper. If it’s an obvious passing situation, or if the team needs to throw the ball, you’d pull a LB or 2 and put in more DBs, but right now this is what a balanced 3-4 front would look like against a balanced 2x2 Spread formation. The OLBs take away any easy inside routes or passes and pursue to take away any cutbacks on a Bubble Screen. The CB and Safety are still in position to take away the screens or anything deep as long as the CBs are able to turn and run, one-on-one with the WRs that they’re covering on the outside.
Even though there are now only 5 defenders in the Box, having those OLBs hanging just outside the Box in the Alleys creates some issues. First of all, who will be the defender who has to contain the edge on either side? More often than not the DEs would attack the inside B-gap, and the OLBs would have outside contain. The NG would more often than not attack the Center directly, and he would be responsible for covering both A-gaps. How are the O-linemen going to climb up to block those LBs?
Here's what it looks like:
The first thing that you should notice is that it’s all but hopeless for the QB to keep the ball on the Read part of the play unless that backside OLB is blitzing or incredibly slow. He should still be out of the play for the RB though. Starting with the Center, he will have a tough time moving the NG, and the NG will be trained to react to the direction of the Center’s first step and attack in that direction. Because the backside Guard (the RG) would be working to combo block him, the 2nd blocker would have to push him in the direction of the play. A decent NG is going to take away the A-gap on the playside for the RB so that he has to at least run around him. Look at the angle of the path that the RG needs to take to get to the backside ILB. If the NG holds his ground reasonably well, it will be a shorter path for the backside ILB to scrape past the NG to the playside than it will be for the backside Guard to climb up to him, and it will be even harder if he tries helping the C to combo block the NG first. If the Center takes that backside LB, the RG would have to block the NG without pushing him sideways towards where the play is supposed to be aiming. The only O-lineman who would have a reasonably good angle for his block would be the Right OT blocking the backside DE, but that’s only if the OT gets his foot into that gap first to gain leverage. A quick DE could shoot past that block and be in the backfield before the RB has the ball.
As difficult as all of that is, it’s on the playside that the blockers will have the most trouble, both because of tough angles, but also because that OLB is a 3rd defender who is lurking just outside the Box. If the DE steps towards the B-gap, who blocks him? By typical zone blocking rules, the LG should take him and drive him to the left and backwards, but that would cut the Left OT off from being able to get to the playside ILB. The O-linemen would probably make a Block Call for them to combo block the DE towards the ILB, then the LG would come off the combo block to intercept the ILB before he gets into the hole. If the DE doesn’t move, or if the ILB is quick or good at fighting off blocks or both, he’s already in position to make a play on the RB. Finally, don’t forget about the playside OLB. This is where Alex Davis really struggled last year, but a decent OLB who reads the blocks should be looking into the backfield while coming across the Line of Scrimmage and squeezing down on the RB to force him towards his teammates in as tight of a space as possible. A very good OLB can make that play at or before the RB gets to the Line of Scrimmage. If you use the OT to block him, the LG has to take the playside DE, and there’s nobody left to block the playside ILB. Even if every block is made, all the D-line has to do is hold their ground, and every gap has a defender standing in it, and every defender’s momentum is taking him closer to where the ball carrier is initially going.
Whether you think the 4-3 is the greatest thing since sliced bread, or if you think that the 3-4 will be tough to find recruits, at least now you know why Nebraska is using it. Keep in mind that in this or any other system, an athlete that is far superior can make plays regardless of scheme, so it’s not as though my high school students can run this offense and beat an NFL team running a 4-3.
Comments or questions?
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Just kidding. 
