Football 101

[BroncoInSkinland]

Table of Contents

4-3 Base Defense
4-3 Under
Defensive Alignment
Gap Names
Linebacker position names
Offensive line mechanics
Pass Blocking
Run Blocking
Technique
Will-Mike-Sam

Edited addition/table of contents: As this thread has the potential of getting very convoluted and possibly hard to follow as a result, I though perhaps a table of contents would be appropriate. As the thread continues I will attempt to keep the TOC up to date. This will allow us to have discussion about the relevant topics, but also keep information at users fingertips if they are looking for quick reference material. If you are posting a new entry that you feel would be appropriate to include in the TOC, please contact me.


I had hoped someone more qualified would start this thread, but maybe I can get the ball rolling and get the education I was seeking in posts that follow. To start, I expect a very basic understanding of the fundamentals of the game. If you aren't sure what Defense, Offense, yards, or a down is check out this site Football 101 - Understanding the Basics of American Football to get a primer on the terminology that will be used in the posts that follow. I will get thins started with the 4-3 Defense.



The 4-3 Defense is the most commonly utilized base defensive formation used in the NFL. It consists of 4 Linemen, 3 Linebackers, 2 Cornerbacks (CB), and 2 Safeties (S). The linemen are broken down into 2 Defensive tackles (DT) and 2 Defensive ends (DE). The Linebackers are usually referred to as strong side linebacker or sam (SL), middle or mike linebacker (ML), and weak side or will linebacker (WL). Strong side refers to the side on which the opposing team plays their Tight End (TE).

The DT's job is to engage the opposing offensive line, and hopefully get through them to the quarterback if the opponent has called a pass play, or to clog the middle of the line if it is a running play. Usually one of the two DT's is a larger, stronger player, ideally around 345 Lbs. This DT will try to push the center (C) of the opposing offensive line back and power his way to the Quarterback (QB), if it is a run play, he is usually responsible for stopping the Runningback (RB) from getting through the gap between the C and the Left Guard (LG). The other DT is usually a smaller, faster lineman ideally around 315 Lbs. He usually lines up to the right of the of the right guard (RG), and on passing plays attempts to speed his way between the RG and the right tackle (RT) to get to the Quarterback. On running downs, his gap assignment is the gap between the RG and RT.

The DE's job is to get to the outside of the offensive line, and push the play to the inside, towards the DT's, as quickly as possible. They line up outside the RT and left tackle (LT), and attempt to use thier speed to get around and to the quarterback on passing plays, or to contain and hopefully tackle the RB on runs.

If the front 4 are good at their jobs, it makes life a lot easier on the LB's in a 4-3. On passing downs the LBs drop back and provide coverage to prevent a short pass. The SL attempts to block the TE or covers him and attempts to break up a short pass. The WL ussually covers the RB who is attempting to run to the outside and provide a dump off for the QB. The ML assesses the situation and either covers the middle of the field should any of the receivers come open, or moves to support whatever part of the field looks the most vulnerable. On running plays, the SL covers the gap between the TE and RT, the WL covers the gap between the LG and LT, and the ML covers the gap between the C and RG.

That is the basic idea behind the 4-3 offense, it is generally considered to be somewhat stronger against he pass than the second most common defense (the 3-4 defense), but a bit weaker against the run. It is also much more static than the 3-4, not allowing as much flexibility with defensive play calls, and relying much more heavily on the blitz to get pressure on the Quarterback unless you have four phenomenal linemen. Additionally it is supposedly more difficult to get the right personnel for a 4-3 defense , requiring 3 big yet athletic linemen and LB's that are very good against both the run and the pass.

If anyone has any corrections or additional thoughts, please post them, I am really not all that much of an X's and O's guy, although I am trying to learn. We could also use someone to tell us what the 3-4 defense is all about.

[OconRecon]

Great start to 101.

[Legacy Fan]

Originally Posted by OconRecon

Great start to 101.

Agreed. And good idea too. Which is why I 3-counted it.

[Neo]

Maybe someone should E-mail this thread to the Browns front office

[BroncoInSkinland]

As we have already gone over in the 4-3 base defense post, during running plays, each player is responsible for a "gap" between two offensive linemen. Most Defensive Coordinators assign names to these gaps for simplicity, rather than having to go through the trouble of saying "The gap between the Center and the Left Guard", they can simply say "the Weak A gap", or "the Strong B gap". Different coordinators sometimes use different nomenclature, but for simplicity, I am going to use the one I am most familiar with.



Above is the 4-3 defense, the gap between the C and LG Is the Weakside A Gap, the gap between C and RG is the strong side A gap. The arrows indicate each players gap responsibility as noted in the 4-3 base Defense post. Note that all gaps are covered by a single player, and that containment is achieved by the DE's on both sides.

------------------------------------

There are of course variations on this defense, one of the most common is called the 4-3 under Defense. The under formation changes which side the 3 tech DT is on to prevent opposing teams from double teaming him.



In this diagram, the larger of the two DT's is labeled NT or Nose tackle, a common designation for the big bruiser up front. As you can see, the 3 tech is now lined up off the LG's left shoulder, prepared to make the speed move and shoot the Weak B gap (between the LG and LT). The linebackers run stopping assignments shift to the Weak A gap, and Strong B and C gaps as a result. The result of this shift means it is almost impossible for the Offense to double team the 3 tech, as the Center has to block the NT, and the LT must deal with the weakside DE. This leaves the 3 tech in isolation against the LG, which is often a good match up for the Defense.

[jason j]

One thing it may help to include, be it a 3 or 4 man front, is a quick explanation of the "technique" positions along the defensive line. So, here goes.

Don't get caught up with the word "technique" though. The term really only indicates the alignment... although some systems dictate that certain "techniques" indicate a 1-gap vs. 2-gap responsibility. It's really much simpler if you just consider it an alignment.

Though the naming conventions vary slightly from system to system, a good rule of thumb is to count the techniques from the nose out. Gaps get odd numbers, men get even numbers. eg. The nose tackle is the zero technique - he plays man up over the center's nose, a 1-technique would line up in the center/guard gap, a 4 technique would be head up over the tackle, and so on. So when someone refers to a 5-technique, he's usually referring to the defensive end lined up in the T/TE gap.

You will also hear occasionally a 2i technique or a 4o technique. This simply indicates the man over defender will align himself on the i-inside or o-outside shoulder of the offensive lineman.

Also, 10-technique, 20-tech, and so on, are the same lateral positions at LB depth. So, a 40 technique would be 4 yards deep head up over the tackle.

Remember this is only a guideline. 3-4 aficionados will often refer to 9-techniques and 11 techniques (which by this count is way more gaps than there are linemen). But they have some subtleties that distinguish them. They also commonly refer to the DE in a 3-4 as a 5 technique, where by the general rule of thumb would call it a 4. You can blame Bum Phillips for making it so hard to follow... for instance; in his original system, the rule holds true until you get to the 8 technique which is actually outside of a 9 technique. So, I'm sorry to confuse matters, but look what I'm dealing with, eh?

Generally, odd fronts (3-4's and 5-2's) have all even techniques: a zero, two 4-techs, a 6-tech, then either a 6 or a 60 technique on the weak side (even though there's no TE to be head up on. You'll occasionally get the 0-4-7/70 set playing the OLBs outside the TE. But, in pro ball they're generally 6's. But, like I said, it varies.

The reason for all this is it makes it very easy to align and realign your defensive front. You can say things like "when they go double TE to the strong side we're going to go eight sixty to that side." Meaning: We'll play the sam backer on the line head up over the second TE (8), and the ted backer off the line head up over inside TE (60).

Or you can roll "double strong" against the same formation (2TE's to the same side). Meaning: Roll two techniques across the formation to the "double strong side" - so the zero technique becomes a two, the four becomes a six, and the six becomes and eight. Typically, if you were running a 60 on the weekside he'd roll down to a 4 or 4o technique rather than play off the ball - although you could go 60-10-40 across - depending on what kind of support you have in the secondary.

And while we're on the subject, let's hit these linebacker names real quick. The 4-3, it's really easy. Sam - Mike - Will = Strong - Middle - Weak. In 90% of the cases the Sam lines up to the defense's left, and the Will to the right. However, some teams will roll a true Sam backer to the tight end side. Generally, when you have TE on the offensive right side, you've got Sam - Mike - Will from the defensive left to right.

The 3-4 gets a little confusing. Mostly because they use the same names for different things. There are two popular naming conventions among 3-4 teams. They are as follows:

SOLB - Sam
SILB - Ted
WILB - Mike
WOLB - Will

SOLB - Sam
SILB - Mike
WILB - Will
WOLB - Jack

Hence the confusion.

The Browns' Eric Mangini uses the second set of terms, so he refers to the strong side inside linebacker as "Mike". In Cleveland Eric Barton plays the "Mike" backer.

I tend to use the "Ted-Mike" system. It saves confusion when moving back and forth between defense and offense.

On that note, it's important not to confuse the defensive naming system with the way that offenses identify the "Mike" backer. To an offense, the "Mike" backer is the center of the defense. He is the 7th defender - he's the protected second level defender. Against a 3-4 that's almost always the weak side inside linebacker. So offenses set their blocking assignments by identifying the "Mike" backer and working outward. Well, in Mangini's system the "Mike" backer is actually the other guy. So, it saves one minor headache to not change the Mike and Will for both sides of the ball.

Hope that helps.

-jj

[Danamal]

Holy hell,
What time does sponge bob cmon!
Really great stuff guys,thanks for sharing.

[BroncoInSkinland]

Excellent post Jason, thanks. I think some of what Jason and I posted contradicted on gap names and positions, to anyone reading that is confused as a result, for the love of God listen to Jason, his football knowledge far exceeds my own. I know this, and have no problem with it, heck, I am just glad to get to read his breakdown on things.

Just to clarify things in my own head Jason, would this be an accurate diagram of all the possible technique positions along the line and for the linebacks? Excusing of course that it gets tricky on the outside where I have the 9/90's right now.



Making this an accurate blowup of the eight sixty example you mentioned...



And also, when using this system, do you refer to the gaps in the offensive line by number, so the Gap between the Center and guard would be the 1 gap? Just trying to nail down some specific names so we can standardize things here and all get on the same page.

[jason j]

Couple of things:

1.) in the 8-60 diagram, that's correct, except for the fact that one of those TE's would be lined up off the ball - usually the one on the outside. He'd be a yard outside and a yard deep in what is called the wing or "H" position.

2.) regarding the gap distinctions, actually, you'd use both. For example, "The 3-technique lines up in the B gap."

You still use the letter system for assignments. A-B-C-D for the gaps. The technique designations replace the old letter system for players. I've never seen it used, but there used to be a letter system for each shoulder of the offensive linemen. It started with E (because the A-B-C-D gap system was already well established). E was head up on the center, F was inside shoulder of the guard, G was head up on the guard, H was his outside shoulder, and so on, for what seems like an eternity. I learned it with the military-type letters - "Echo strong Kilo/Kilo November - Ted/Will Juliet - Mike Echo" Which means a half man shift for the nose (Echo strong), the ends are playing outside position (Kilo/Kilo), and a full man shift for the three remaining backers (Ted/Will - Juliet = head up over the tackles, and Mike - Echo = head up over the center).

That system has several limitations - not the least of which is it takes a half an hour to call plays this way. The other is that it doesn't identify depth - and you end up with defensive lineman singing the alphabet trying to figure out if they're supposed to play on the inside or outside shoulder. Plus "mike" is not only a linebacker, it also means head up on the tight end - which is a place the Mike backer rarely lines up. It's a mess.

The number system (or "technique" system) was just a simplification of that. I can't imagine teaching defensive linemen to translate that many letters into three dimensions. But a good demonstration of the simplification is this: That ridiculous call that sounded like I was trying to get ground clearance to land an F18, under the number system sounds like this - "zero strong double 4o - 9 roll 20" It's the same call, Zero strong - is a half man shift for the nose; double 4o is outside technique for the ends, and 9 indicates the SOLB is on the line outside of the tight end; and the three up backers are rolling 20 - meaning linebacker depth 2 techniques to the strong side. (If it was to the weak side, it would say "roll 20 weak.") It's assumed that you are rolling to the strong side unless otherwise indicated.

There, that should be clear as mud.

-jj

[Shep]

JJ's in da house! Whoop, whoop. Or so the kids say.

[Masters]

Originally Posted by Shep

JJ's in da house! Whoop, whoop. Or so the kids say.

I think they stopped saying the 10 years ago Shep

[Vegasdogg]

Cool Sticky. Good stuff guys.