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Spring Game Run Defense

Cal’s New 3-4

This is part of a series on our new coaching staff. For more information, check out these posts as well:

Breaking Down Justin Wilcox

Steve Greatwood’s Zone Schemes

Creating Matchups with Beau Baldwin

And my E-Book (PDF): Beau Baldwin vs. WSU (2016)

Cal’s got a brand new 3-4 defense, and it certainly marks a departure from the defense that we’ve been playing for the last few years. In this post, I’m going to look at how our new defense was set up to defend the run during the spring game. After an introduction to run defense in general, I’m going to talk about how our 2-gapping 3-4 is supposed to work, and then I’ll break down some plays from the Spring Game to show what benefits we’ve derived from making this switch, and what problems might arise as the season progresses.

Run Defense Preliminaries

Before talking about run defense in the spring game, it's good to look at how coaches and players talk about defending the run more generally. Everyone who'd want to click on a story like this has probably watched a lot of football, so we've all heard about “gap integrity.” That's a good place to start. From the defense's perspective, they don't need to defend the offense's blockers per se; the ball carrier can't run through another human being, and so what the defense actually needs to defend are the spaces (or “gaps”) between blockers. If they can plug up all of those gaps, then the ball-carrier will have nowhere to go:

Gap Integrity

When a coach is installing a defensive front, he needs a quick way to tell his guys which gaps they're responsible for. To do this, gaps are generally labelled with letters. The gaps outside the Center are called the A-gaps, the gaps outside the OG's are the B-gaps, and so on:

Labeling Gaps

When installing a front, then, you can say things like “In this front the NT has the strongside A-gap, the MLB has the strongside B-gap, etc.” This gives each defender his gap assignment on any particular play.

Assignments are obviously important, as they tell each defender what his responsibility is. Equally important, however, is each player's alignment. Let's consider the following stunt:

Stunting to Different Gaps

In this stunt, the DE lines up in the strongside C-gap (between the RT and TE), but his assignment is actually to defend the next gap inside (the B-gap between the RG and RT). The SLB lines up in the D-gap but stunts to the C-gap, and the MLB scrapes over the top to defend the D-gap. On this stunt, alignment and assignment aren't the same thing, and are two equally important pieces of the puzzle. By lining defenders up in one gap but making them responsible for another, the defense can create movement in the front and confuse the offense's blocking schemes.

This all makes it useful to have a separate system for talking about a defender's alignment, and to do this coaches talk about different defensive “techniques.” Techniques are labelled with numbers instead of letters. Even-numbered techniques tell a defender to line up heads-u, or directly across from a particular blocker. Heads-up over the C is called a 0-technique, and the numbers work out from there:

Even Techniques

With one exception, if you want a defender to line up with an inside shade on a blocker, then you can add an “i” to the even-numbered designations above. So, an inside shade on an OG is called a 2i, an inside shade on an OT is a 4i, etc:


For reasons that I've not yet been able to glean, an inside shade on the TE breaks the pattern and is called a 7-tech.

Odd-numbered techniques tell a defender to line up with an outside shade on a particular defender. A 1-tech is a shade on the C, a 3-tech is an outside shade on a guard, and so on:

Odd Techniques

An outside shade on the TE is a 9-tech, because the 7-tech label was already used to refer to an inside shade on the TE.

At first, it might seem like overkill to have three different ways to line up over the same blocker or gap; a 2i-, 2-, and 3-tech are all just slightly different ways to line up over an OG, for example (inside shade, heads-up, and outside shade respectively), and a 1 and a 2i (a shade on the C and an inside shade on the OG, respectively) are just different was to line up in the A-gap between the C and OG. These minor tweaks can add up to major differences, however. Let's look at some different techniques against one particular kind of block: the “reach” block.

When a blocker is trying to “reach” his defender, he's basically trying to cross his face and seal him off from where the run is going. Here, for example, is a C reaching a 1-tech NT:

Reaching a 1-Tech

When the NT is shaded over the Center in a 1-tech like this, this assignment is manageable. It becomes more difficult if the NT is shifted over a few feet into a 2i (inside shade on the OG), simply because this alignment puts the NT farther away from the C. Furthermore, because a 2i is lined up over the OG, he can force that OG to block him instead of releasing up to another player:

Reaching a 2i

If the NT can force the RG to block him like this, then it buys time for the MLB to react and make a play. Changing the technique of one player can therefore create a ripple effect that impacts other players.

Whereas a 2i might be hard for the Center to reach, a 0-tech will be comparatively easy and, depending on the blocking scheme, can even pull the LG into the block:

Reaching a 0-Tech

Slight changes in a DL's alignment can therefore change up angles and matchups in run defense. Furthermore, these changes have implications for the rest of your front defenders, and even for the rest of your defense as a whole.

1-Gapping vs. 2-Gapping

These different techniques lead us to another assignment issue, and to the difference between a 1-gapping vs. a 2-gapping defensive line. Our former DC, Art Kaufman, belonged to the Miami 4-3 school of defense. In this defense, each player in the front is usually responsible for one and only one gap (the defenders are 1-gapping). They usually line up shaded into the gap that they're defending (meaning that they play lots of odd and i techniques), and are primarily responsible for shooting through that gap and into the backfield to create disruption (or at least that was the theory):

1-Gapping 4-3

1-gapping is generally associated with 4-3 defenses, but there's absolutely no reason that you can't 1-gap from 3-4 personnel. Many modern 3-4 defenses do shade their players and have them 1-gap most of the time:

1-Gapping 3-4

This is the kind of thing that you'll see a lot from Clancy Pendergast, for example.

Both Wilcox and DeRuyter are 3-4 coaches, but they (and Coach Azzinaro) favor a more old-school approach to the 3-4. This approach plays with a lot of even techniques, and uses a lot of 2-gapping along the DL:

2-Gapping 3-4

2-gapping DL aren't trying to shoot gaps. As the name suggests, they're responsible for the gaps on both sides of their blocker, and so they want to use violent hands to engage that blocker and control him, so that they can then shed him and fall into whichever gap the RB chooses. Check out the following play by #96 Tevin Paul, for example:

Note how Paul takes on his blocker heads-up, gets hands on him, and then disengages and falls inside once the RB makes his cutback.

That's how 2-gapping works for one individual player. How does it impact the defense as a whole? A major key in a 2-gapping 3-4 defense is for the DL to command double-teams, which let the DL eat up blockers and free up the LB's to flow to the ball. Here's the full diagram for the play that we just saw:

Paul 2-Gapping

The offense is running Inside Zone to the left here (for more info about the blocking assignments, check out my post on Steve Greatwood here). The C, RG, and RT are going to be one-on-one against the NT, the blitzing WILB, and the DE to the right side of the diagram. The TE (on the right side edge) is going to cut-off the Rush LB (J) just long enough to prevent backside pursuit before releasing up for a second level block on the FS. As we saw in the video, Paul controls the RT and makes the tackle, but another important contribution comes from #92 Gabe Cherry, the DE to the offense's left. On this play, Cherry doesn't make the play himself, but he draws a double-team from the LT and LG. This means that there is no blocker left for the SILB, who is free to flow to the ball:

Double Team Frees up SILB

Now you can go back to that last video and watch the left side of the line, this time to see how our DE occupies two blockers and frees up the SILB to get in on the stop.

The 3-4's Impact on the Numbers Game

2-gapping your DL can also change up numbers in run defense. To see this, let's compare a hypothetical run against a 4-3 defense to a play from the Spring Game. First, here's the hypothetical play against a 4-3:

Zone vs. 4-3

Here the play is going to the right, and the defense in in a six-man box. There are three defenders to the left of Center (DE, MLB, NT) and three to the right (DT, WLB, DE). This makes sense, because there are three gaps to the left of C, and three gaps to his right. A 1-gapping 4-3 defense will designate one player for each of those gaps.

Because the NT is shaded to the Center's left, the C should be able to get free of him, which will let the C, RG, and RT block the three playside defenders (DT, DE, WLB). On the backside, the LG can pick up the shaded NT, the LT takes the MLB, and the backside DE is unblocked (the offense will account for him with the threat of a QB run/roll out).

If we shift the NT over to a 0-tech, however, then the numbers change:

Outside Zone vs. 3-4

This is still a 6-man box, but the defense is now shifted ½ a man over to the offense's right. In the 4-3, we saw that the defense had three players on each side of the C, but in this 3-4 front the defense has 3.5 defenders to the Center's right (the DE, WLB, J, and half of the NT), and 2.5 to his left (the DE, MLB, and half of the NT).

This shift to the right of the diagram causes two new problems for the offense. First, because the NT is heads-up over the C, he can occupy him and prevent him from getting a clean release to block somebody else. If the NT can use up the C, then the offense is left with two blockers (RG and RT) to block three defenders (DE, WLB, and Rush Backer):

NT Occupies C

If the C is able to get away from the NT and over to the playside, then it will be up to the LG to block the NT. This will be tough to do against a 0-tech, because a 0-tech is lined up directly over the C, and so is reasonably far from the LG.

On a play from the spring game we saw these factors at work. In the following video, watch how the NT is able to prevent the C from getting a clean release to block the blitzing WLB. Second, notice how the LG is unable to get to the NT, who gets penetration and makes the play:

Creating Confusion: Mixing up 1- and 2-gap Assignments

Another point about playing even techniques like this is that it creates uncertainty for the offense's blocking schemes. When the DL lines up in even techniques, they could be playing 2-gap assignments like we've just seen, but they could just as easily be slanting to one side or the other and 1-gapping. Here's a potential slant to the offense's right:

Slant Right

And here's a potential slant to the offense's left:

Slant Left

Both are equally possible from even techniques, and of course 2-gapping would also be an option from these alignments. The offensive blockers don’t know which side their DL is going to take. As an example of the confusion this can cause, here's a play from the spring game with Tevin Paul 1-gapping and attacking the B-gap:

Here there is apparently a mix-up between the C and RT about who should take Paul, who therefore gets into the backfield unimpeded.

Although I've emphasized 2-gapping in this post, there were many occasions in the Spring Game where at least one player on the DL 1-gapped like we saw in this last video, and we have several calls that combine 2- and 1-gapping techniques.

Downsides to a 2-Gapping 3-4 Defense

One downside to 2-gapping is that there is a lot of reading and reacting going on. A defensive lineman takes on his blocker heads-up, and only falls into a gap once the RB commits to it. Behind him, the LB's are reading blocks and flowing to the ball instead of just attacking a gap. We can see the downside of this on the following play:

Here the DE holds his ground reasonably well against the LT, but is unable to shed his block cleanly enough to get a hold of the RB. The LB stacked behind him is left waiting for the RB to choose a gap, and so has to wait to attack the line of scrimmage. Notice how he doesn't come downhill until the RB is already up to the line, and he doesn't make contact until the RB already has a 3-yard gain. In a 1-gap defense, the assignments of both the DE and the LB would've been pre-assigned, and so would've allowed them to play more aggressively, defeat blocks more easily, and clog up the gaps on both sides of the blocker.

Another downside comes from the numbers situation on the line of scrimmage. Because the 3-4 has one fewer DL, it's easier for the OL to get double-teams on the DL:

On this play, notice how the DE gets backed up right into a LB, which makes it hard for that LB to react and get to the ball. This is more of a risk in a 2-gapping 3-4 front than in other kinds of defense.


Overall, my impression of the Spring Game was that the change in defensive scheme on the DL, combined with new Coach Jerry Azzinaro, has probably made the biggest immediate impact on our team. We don't have three beasts who can 2-gap on the DL and hold the line of scrimmage all by themselves. We do, however, have some players who can hold their own at both DE and NT, at least against our OL. We also have some smaller DE's who get pushed around sometimes, but who can shed blockers and shoot gaps, especially when asked to 1-gap. It does look like we're playing more on the other side of the line of scrimmage than we were last year. I didn't see any dominant all-around players in the Spring Game, but I did see some solid role players with different skillsets, and that's a good place to start in the college game.

I don't yet see the same impact with our LB’s in run defense, which is a potential problem that's carrying over from last year. Hopefully the LB's will play faster and more confidently with more time in the system, but right now I’m still seeing missed/drag-down tackles. At any rate, that’s what the summer’s for, and I look forward to seeing what improvements happen over the next few months. Go Bears!