Sunday, January 2, 2011

Viewers Choice: How Coverage Determines the Front

This Post is in response to the question posed by ABC...
In regards to an article by Steve Axman on how Coverage and front's must relate to each other to be sound.

I am going to simply talk about coverages with a 4 man rush, for simplicity sake, I will leave zone blitzes out of this post.

In the article by Axman he discusses everything out of a 3-4/5-2 defense... I feel pretty comfortable explaining this further because I have even though I have worked with multiple D Coordinators int he 5 years I have been coaching, they have all been 3-4/5-2 coaches.  This whole post will be based on a 3-4 defense but the principles behind it apply, or at least should apply to any scheme.

I want to first make a statement, because ABC wanted to know if this concept is easier to understand when dealing with a 4 man front.  It is easier to grasp in a 4 man front simply because those 4 are rushing every play without change...The DBs and LBs will have different responsibilities depending on coverage but those 4 down linemen will be rushing every snap.

In a 3 man front (whether 3-4 or 3-5)  the down 3 are rushing and 1 more player will be coming on most snaps giving a 4 man rush.  So after the snap it will either look the same or very similar to a 4 man front but the 4th rusher can change depending on coverage.

Coverage Determines the Front

When creating a defensive scheme, one must first start with the coverage they want to run.  This coverage will then determine what front they can get into and which players are available to rush the quarterback. 
It is important to see how the coverage you play correlates with the secondary's run fits within your scheme.  Players need to understand what it means to be a force player, or an alley player, and where they need to be on certain run plays.

I will start by explaining, in my area, the most common coverage around, your standard Cover 3 Defense (Axman also refers to it as Sky in his article)

I will explain things first against a basic pro style formation, just for simplicity sake. 

So we will begin with the deep 3. Corner, FS, Corner

They of course split the field into 1/3s, do not get beat deep!
Typical alignment is for corners to be 7+ yards deep at the snap and staying in their deep 1/3. On a run play they are secondary run support, they should keep all run plays inside of them and just make a sure tackle.  In cover 3, when they are making tackles it is preventing the big plays.
Free Safety should align to the middle of the formation, keying the strong side #2 for his run/pass read.  He has deep middle on pass.  on a run he is the alley player.

In Cover 3 the Strong Safety is in a rolled up position, to the strong side.  He has the flats or curl/flats, on pass.  He is the force player on outside runs.  He is to force all outside plays back inside of him.

Now that we have seen what the DBs are doing, I will illustrate how this coverage dictates the front that we should run.

Some clarifications of my drawing, I used this in a PPT playbook I made up for my self when I took a DC job a year ago. 
D = SS
ILBs = L and R
OLBs = also L and R
I will differentiate by writing LILB or LOLB etc.

Now let's discuss the above diagram. 
The 4 DBs have given us coverage in the 3 deep zones, and the curl/flat zone to the strong side, but now we need curl/flat zone to the weak side.

This becomes the responsibility of the LOLB.  His job is just like the SS, curl/flat zone and force player on run plays.

Because he will be vacating, we need a edge rusher/contain man to that weakside. 
So the natural/simplest answer is to slant the Down 3 DL to the weakside.
By Slanting weak (as shown) we get a contain rusher on the weakside and account 1 player per gap.  Defense is all about gap integrity and support. 

The 2 ILBs have the hook zones on pass coverage.

Now that we have accounted for 3 deep zones, and 4 underneath zones, we have 1 left over defender, our ROLB or the strong side OLB.  He is not needed in pass coverage so we can bring him off the edge to the strong side ( or bring him across the TEs face)

Against a spread look I would adjust like this

Now we are in a spread look. I would call this strong Left because the Back is also to the Left.
This puts our SS (D) to the left side.  Everyone elses job remains the same.  We slant to the weak side (right) to get an edge rusher/contain man to the weakside.
The only actual difference is now that there is twins to the RT side, our ROLB must remove himself from the box, at least splitting the difference in order to cover up the #2 WR and effectively cover his curl/flat zone. My base rule in this defense is for the Weak OLB (ROLB in this case) to split the difference when he has 2 WRs to his side. 
Just a very small change, every one's job remains the same.
The coverage (3) dictates which way to slant our DL, and which of the 2 OLBs will be rushing.

Cover 2
Now I will Explore Cover 2

We will start with the Safeties, positioned on each hash.  They have Deep half and are the alley player on runs.

The Corners are up jamming #1 WR, funneling him inside to the Safeties.  They have Flats on Pass, and now they are the Force players on outside runs.  They must force all run plays back inside.

In Cover 2, the 4 DBs take the 2 Deep Zones, and the 2 Flat Zones.  We are left with the 2 Hook/Curl Zones, and the middle zone.

We will drop the Strong side OLB (ROLB) into the hook/curl zone on pass.

The SILB(RILB) drops into the middle zone.

The WILB(LILB) drops into the weak side hook/curl zone.

Now we have all 5 underneath zones covered, and both deep zones covered.

Dropping the Strong Side OLB (ROLB) means we need a edge rusher/contain man to that side, so we will Slant our DL to the STRONG SIDE in Cover 2

Since all pass zones are accounted for, we are able to bring the WOLB (LOLB) off the edge, giving us our 4th rusher.

Again, the coverage dictated our front and run support.  Playing Cover 2, forces us to slant Strong.

Cover 1  (Man Free)
Now to explore Man Free Coverage. 

Now I must add that playing man Coverage does allow you to bring a 5th rusher, however you lose a lot of your run support because now your DBs are locked man to man, so they can not have their eyes in the backfield providing your run support.

Corners have #1 WR man to man
FS plays Center field, he is the only DB who can have his eyes on the play and he is still able to run the alley.  His job in Cover 1, is to save touchdowns. 

the SS has the TE man to man.  His alignment can be played with depending on his skills and the TE he is up against.  Some guys want to be in his face pressing, others do better playing off.

Both ILBs are responsible for the RBs out of the backfield.

that is it for pass responsibility, and we are still left with both OLBs, so they become our rushers.  Now that we have 5 rusher we can do multiple things up front.  We can slant strong and bring 2 off the strong side edge.  We can pinch our DTs and bring OLBs off the edge, really just about any thing will be ok here as far as a twist or stunt, as long as we have someone assigned to every gap.  In the diagram I have the DL slanting Strong so we can have a defender in every single gap and bring 2 off the strong side if the TE releases. 

Again the draw back of playing Man is that you lose out on those DBs with vision on the play, and therefore lose your secondary run support.  You risk getting beat deep.  That said in the past we have often have better athletes than our opponents so we have played a lot of man to man, figuring we will get to the Qb by bringing the extra man, before we will get beat in coverage.  This has worked well for us a good deal of the time, but we have been burned in it occasionally. 

Coach ABC,
I hope this has helped to clarify the idea of how your coverage will determine what you are doing with your front and how they tie into one another. 


  1. Coach Dudley

    I am highly impressed. Your football knowledge is only surpassed by your ability to share it with others in simple terms. The explanation now makes so much sense.

    I will further study it in the very near future. After the initial read, I had a couple 'what if we flipped things the other way' questions... I may now be able to answer these myself, or I will post again to pick your brain if needed.

    Keep up the great work on this blog...and let us know next time your taking more requests for articles.

    Sincere thanks.

  2. Coach Dudley,

    I re-read your article several times in conjunction with Axman's article. I think I now understand the concepts pretty well and have been able to apply them to other situations. I still have a couple questions remaining however.

    In cover 2, it is not clear to me why one makes the decision to designate the strong OLB as the Curl zone defender.

    Axman says that it is because "the main permimeter (run) support defender is weak...". My understanding of the meaning of 'the main perimeter support defender" is that is the "force" player, which in cover 2 is the CB, both on the weak and strong side". I must be misunderstanding something here.

    In your article, I am not clear why this decision is made, but I interpret that it was perhaps based on passing considerations, to match the tight end on possibly a better pass coverage player if his route leaves him on the strong side of the field (???).

    My other question relates to 4-3 fronts. You have clearly indicated that 4-3 is simpler as the rushers are already identified. Responsibilities of some 4-3 front players may also be dictated by the coverage, i.e. weak OLB in cover 3 sky. I am trying to find if coverage may dicate other things in the front in order to maintain the integrity of the front/coverage relationship...but can't seem to find any. Would coverage dicate whether the noseguard would work to either the strong or weak A gap? would coverage dicate which side would be the Rush End? would coverage dicate whether an over or under front is required to maintain the integrity of the front/coverage?

    Thanks for sharing your knowledge.

  3. For the 4-3 your DEs always will play for edge pass rush and outside contain, you move your DTs around to strength in order to keep your gap integrity and account for all of the gaps.
    The Beauty of DL play in a 4 man front is that it , in my eyes, is very simple, they have simple alignment rules, and just attack their gap/man, and maintain their gap integrity.Generally you see DEs outside shoulder/eye of the tackles, and DTs will play the strong side shoulder of the guards. Pretty basic defensive structure.

    The coverage in a 4 man front relates to who has force, and where are everyone's run fits based upon who is responsible for which gap.

  4. As far as dropping SOLB in Cover 2, that is just how it was taught to me, but looking at it , it seems that it would be easier for him to drop and cover that curl zone against the TE on a quick pass, than sending him and getting the SILB to rotate over. On that weak side you will see the LILB has no immediate threat to his drop, so he has time to get into it.

  5. Tnx for the reply. The explanation for dropping SOLB in cover makes full sense.

  6. in your 34 explanation you align the ss to the same side as the back but in that offense the back is surely more inclined to run to your right off the qb zone read, does tnhat come into your alignment at all?

  7. DME,

    against a even spread set like that, you become balanced up because the WOLB displaces from the box and essentially mirrors the SS.

    So it really doesnt matter that you have the SS to the RB side, I actually didnt even pay attention to the back when I drew it up. My base rule is SS goes to the strong side, when it is balanced he automatically goes left (to the offense's right, because most offenses are right handed and throw and run more to the right)

    Now I might game plan differently if a team was doing something special but every DC has their own preference to how they treat strength against 2x2. They will usually choose from:
    -Automatically left
    -to the RB side (to some coaches that is essentially trips to the left side, they cant the RB as the 3rd WR)
    -and lastly, as you mentioned, opposite RB

    Either way you are getting an overhang/force/flat defender on each side

    the key is that your entire defense is seeing the same thing, and your backer makes the appropiate strength call. Doesnt matter what he calls really as long as everyone listens. You will get SS going to whatever is deemed strong, line slanting weak. SOLB coming off edge, and WOLB displacing from the box and mirroring SS

    Basically at the end of it all, it takes care of itself by following their assigned rules

  8. Ok thanks coach, i was more interested in how you determined strength v balance. so that clears it up. just found this blog and im enjoying the articles. thanks