The 4-3 'Flex' Defense: The Basics As I Know Them

Kinda The Norm, But Not Really...

My former HS head coach was a very practical, pragmatic guy and a pretty damn good coach. I love the guy, but he wasn't for everyone. As I've said before, his defense was very execution and technique oriented, without a ton of frills and doo-dads. I called the same basic call "Eagle, 87" for at least 90% of my defensive plays. We played the hell out of that Under front, Quarters coverage, with great results at times. When he left to become the header at the local CC, he found himself in the interesting situation that he was inheriting a DC who was very good, but ran a scheme that was different from his. Recognizing that this was an opportunity where he needed to embrace the issue, he kept the DC and is the head coach slash DB coach. Theirs is a funny relationship: the DC has control over most things, but the HC still gets to pull the HC card when he feels something is unsound. They make it work and have routinely fielded a very exceptional defense that's unique and personnel flexible, in my mind.

Alignments And Responsibilities

Their "Down 3" align in fairly typical alignments for typical 4-3 players of their positions. Their Rush End is outside shade the OT to the weakside, the Nose goes to inside shade of the OG to the weakside, and the End lines up outside shade the OT to the strong side. The interesting player is their "Flex" spot, who can really do a lot of things for them. Some years he's a souped-up linebacker and hits his fit, usually outside shade of the OG, on a roll. Others, he's a true-blue defensive lineman and is just playing out of a two-point stance slightly off the ball. They fit the spot to the player and his ability, which I absolutely agree with philosophically. This last season and the coming season their Flex has been a 5'11 235lb MONSTER of an athletic specimen from a local team. He plays it both ways because he can.

Their linebackers are an interesting mix of body types and skill sets. Generally their Sam is a strong-safety type because they see lots and lots of 20 personnel offenses, so they usually elect to go with a strong, athletic runner over most teams prototypical Strong Outside Linebackers. Their Will plays with his heels at 4.5 to 5 yards, responsible for B gap weak, and reads the guard in front of him for his fit. He's your usual LB without any terribly restrictive needs other than the ability to take on an Iso from a FB in B gap. The Mac backer is the other fun player in their scheme, in my mind. He lines up at 7 yards deep and is expected to be playing down hill with a full head of steam on any kind of run play. Moreover, he's supposed to be a big, strong, physical kid who can run down plays. Their ideal is a guy in the 230+ range with at least 4.8 speed.

Because of their over front alignment (-1 NT, +3 Flex), the Mac backer is, in theory, not to be touched by an offensive blocker. The 3 tech flex protects him to the strong side, preventing teams from running isos directly at him, unless it's in A gap, where he will be expected to spank it and spank it hard. Likewise, anything run away from him will have a hard time getting to him thanks to the Will and Nose's presence. The Mac is supposed to make lots, and lots, and lots of tackles and hopefully bring the party when he does.

Secondary-wise, they run cover 3, cover 2, and quarters out of a fairly traditional 2-high coverage. Coach doesn't believe in doing a ton of different things, he'd rather be damn good at a few things and do those things anywhere and against anyone.

Why I Like It...

Being a coach in a 3-4 scheme, with the right personnel I could easily see us doing something very similar to it. In fact, the reason I even know what I know of the scheme is because I was close to installing a package with it this season. We had a linebacker that had spent the last two years as our 3 tech in the old scheme before moving the Mike this season. I thought it was a natural fit for us and would fit easily into our adjustments, but didn't feel comfortable pulling the trigger on the installation. I didn't feel it was unique enough from our 4-man front we stem to in order to warrant taking practice time to put it in. This isn't to say that it'll never happen or I don't actually think it's very useful, I just didn't feel good about it given what we were already dealing with.

It's flexible to your year-in, year-out personnel changes that you will deal with at the high school level, which is attractive to me. A very popular poster from Coachhuey is quoted as saying, "Play defense, not defenses" and I think this scheme allows you to play defense with different personnel without changing defenses, if that's clear. Some years you'll have a bumper crop of linebackers, in which case you can run this with a linebacker body at the Flex. Others, you'll have an influx of big boys and you can play a heavy at the Flex spot. You can change what you emphasize without changing what you practice and what you do.

If you're running with 3-4 type personnel, you can do a lot more blitzing and slanting and attacking with your front. If you're running 4-3 personnel, you can rely a lot more on execution and simplicity. You can line up in it from 3-3-5 personnel, 4-2-5 personnel, whatever. It's a very, very flexible scheme in my opinion and I think that contributes a great deal to anyone's defensive repertoire.

I plan on doing a write up in the next day or two on a few possible stunts and coverage combos I'd run, if it were my baby.