3-4 Run Defense: Part II

This is Part II in a series of posts on run defense in the 3-4 defensive scheme. We will look at defending against 21 personnel today.

While there are eight possible gaps to attack in the running game on offense, the gaps don't necessarily come from just the offensive line's alignment. In the case of 21 personnel, when you have 2 backs and 1 TE, the FB is the person who provides that eighth gap, because wherever he goes adds an extra blocker for the offense, and therefore an extra gap to fill.

Let's look at the 3-4 against a pro-set, or today's modern I-formation.

3-4 Defense vs Pro-Set

We have set the formation strong right, to reflect the tendences of most offenses, which are usually right-handed. Across the front going left to right, we have a 7, 3, 1, 3, 5 alignment as we go from SOLB, SDE, NG, WDE, and WOLB. The Mike ILB is in a 10 alignment over the center, and the Will ILB is in a 30 alignment behind the WDE. The Strong Safety (SS) is cheating into the box, giving us our 8-man front. The six men on the LOS on offense give us seven gaps to defend; the SS gives us an eighth man to defend the eighth gap presented by the FB. The LCB and RCB are aligned off the WRs, giving them the ability to drop into zone coverage and move up in run support if needed. The FS is aligned deep, ready to play centerfield and cover the deep passing game, or clean up anything that escapes the 8-man front.

You will notice that the inclusion of the SS in the box gives us four men to either side of the formation; the SOLB, SDE, NG, and SS to the left, the WDE, Mike ILB, Will ILB, and WOLB to the right. This is to balance out the defense, and prevent the defense from outnumbering us with an extra man on the strongside. Now the QB can't just walk to the line, count the front, and run to the right side every time; the extra gap is accounted for, and the SS has to be accounted for.

Against an I-formation pro-set, what would we normally see in the running game? You'd see Iso, Lead, Trap (Dive), Power, Toss, Counter,and maybe some Option. If the offense is a true pro-set and doesn't feature a running QB, you can eliminate the option, which simplifies what you need to defend. You'll see Iso run to the strong A-gap and weak B-gap, Trap (Dive) run to the A-gap weak, Lead run to both B-gaps, Power run the the strong C-gap, Counter to the weak C-gap,  and Toss run to both C-gaps. Unless you are playing a team coached by Frank Solich, you won't see Trap until 3rd down 90% of the time. You will see Counter run only about 10% of the time, and only after they see the LBs cheating to stop Power. When the offense is on the hash near the sideline, they won't run Toss or Power weakside, because the sideline acts as an extra defender, and it is too easy for the defense to stretch the play out. These are the plays you'll see from 21 personnel in pro-set, and with some film study to note tendencies, and simple logic dictated by down, distance, and location, you can deduce which plays they will run when they will run them, and shut them down.

What about a power-I formation, you say? Many teams break the I and align their FB to the strongside, giving the defense a different look, and giviing the offense a numbers advantage on the strongside with the FB aligned on the right (the defense's left). Let's look at this formation:

3-4 Defense vs King Set

We call this formation a King set. You'll notice we have slightly adjusted the alignment of our 3-4 defense, moving the Will ILB to a 20 alignment, the Mike ILB to an 11 alignment, behind the 1-tech shaded strong. We do this because with the FB on the strongside to push the fifth gap on that side, we want a fifth defender so we still have a numbers advantage versus four blockers.

What plays will we see from the King set? They can't run Iso to the weak side, but they will run Counter weak. They can run Power to the strongside, Toss to the strongside, and some Zone (Inside). If you are dealing with a mobile QB, you could see option out of this set, but not with a standard drop-back QB.

What if they put the FB on the weak side? We call that a Queen set.

3-4 Defense Vs Queen Set

Notice that the line is still a 7, 3, and 1 tech on the strongside, and a 3-tech on the weakside, but we've moved the WOLB out a little, almost to a ghost 9-tech, so he can get outside leverage on the FB to the weakside. The Mike ILB shifts over to an 11 alignment, and the Will ILB moves to a 30 alignment behind the weak 3-tech. We're still keeping a balanced 8-man front against their shift.

What plays will we see from the Queen set? They can't run Toss to the strongside, because there is no one there to block. They can run Counter to the strongside, and Power to the weakside, but it will be ugly. They can run a lot of Inside Zone. Queen set isn't a common formation, but when you do see it, the offense is limited to the number of plays it can run out of it.

What about teams that utilize an H-back, both as a blocking FB and as an extra blocker out on the TE like a wingback?

Against an H-back stacked at FB, you just treat it like the I-formation, and your defense reads and aligns accordingly. Against an H-back aligned at wingback strongside, you will shift the alignment of your personnel. Your SOLB will move to a 9-tech, the SDE stays at 3, the NG moves to 0, then WDE is a 3, and the WOLB is a 5. Your Mike ILB shifts over to a 30 tech, while Will moves to a 10 tech. You want five defenders against the strongside to contend with the fifth gap the H-back represents. As far as plays to expect from this formation, Power is to the strongside is obvious, and probably the most prevalent playcall, Counter to the weakside, and Zone (Inside and Outside) to the strongside. Otherwise, you treat this formation like it is the King set, and defend accordingly. If they shoft the H-back to the weakside, which evens up the formation, and gives you eight straight gaps, you treat it like an Ace set, and defend accordingly.  

21 personnel is a popular grouping to run out of for many teams trying to run a power offense today, but with proper alignment and film study, the 3-4 can be effectively utilized to neutralize all of these formations.