DK Note: From the archives -- this excellent article by Mike Chan was originally published on February 18th, just following the Seahawks' Super Bowl victory.
One of the main reasons that Seattle Seahawks' run game has thrived consistently for the past three years is due to the fact they run the Zone Blocking Scheme (ZBS) with great commitment. What is the Zone Blocking, and why is it successful? Let me help you answer that question.
To begin, we must consider the philosophy of the ZBS to be very unorthodox compared to the what the game was originally designed to be. The core of this scheme relies on teamwork and ganging up on defenders rather than specific assignments. It is the reason why it is difficult to draw up a ZBS play, because offensive lineman probably won't know who they will block until they are set at the line of scrimmage. However, this allows the team to predicate how to open up running lanes based on specific looks by the defensel; so, whether there are eight guys in the box or six, the trenches are always prepared to do their job.
Another reason the ZBS is successful is due to its balanced nature. Standard offensive lineman are typically asked to either run block and drive the line of scrimmage forward on a play, or pass block and move backwards to form a pocket.
In the ZBS, there is no such distinction, because the most important direction in ZBS for a offensive lineman is laterally in either direction. Having the offensive line either move right and left instead of back and forth forces the defenses to be more attentive in recognizing whether or not the offense is passing or rushing.
ZBS requires a specific type of offensive lineman to work. You can't just be big, you can't just be tall, and you can't just be fat either. Can your center immediately recognize what front the defense is in? How good is your right guard in terms of cut blocking? Does your left tackle have enough athleticism to swing around and get the correct angle on the defensive lineman? All these questions are ones that a coach needs to ask before even trying to implement the scheme. If there aren't any concerns, then it is time to move on teaching them to proper skills.
We begin by looking at the footwork that a ZBS lineman needs to understand. This may seem complex at first, but take a look below. Keep in mind this is only designed for run blocking:
The A steps signifies a forward block, which is the equivalent punishing a guy away from the line of scrimmage - pretty self-explanatory. The B steps are what is so special about the ZBS. Instead of stepping forward, a ZBS lineman is asked to step in a 45 degree direction towards where the play is going. This allows players to get leverage on the defender more quickly and "turn" him away from the play. Taking a B step is also the first part of getting a cut block down - another key skill required to succeed in the ZBS.
The C, D and E steps takes this a bit further - I stated in the beginning how ZBS is deceptive because OL move left and right vs. backwards and forwards. With a offensive lineman taking a C step the play is usually designed to be a stretch run, and the philosophy of run blocking shifts from trying to beat your man forward to getting him turned toward the outside. The running back essentially follows a wave of his own blockers until he finds a hole to cut back inside on.
Obviously, doing this proposes a series of challenges for the group - the least of them being on the right page. ZBS requires a lot of time, effort and coordination to be effective. And as many have pointed out, the goal for a good ZBS offensive line isn't just blocking - it is to be synchronized together in terms of their footwork and movement, akin to something you see in swimming pools except with 300+ pound behemoths.
What scaffolds this development is the rules that are at the core of every ZBS - and it is with these rules that offensive linemen use to decide on their blocks.
As the name suggests, Zone Blocking Scheme is quite literally blocking a zone, or an area of the field, rather than man. How players are able to recognize which area they block (or rather, where their block leads them to be) is a matter of simple recognition and being able to answer three questions prior to having the ball snapped:
Am I lined up to on the play-side or weak-side of the play?
Am I covered, or lined up in front of a defensive player?
Is my teammate, who is next to me, covered or lined up in front of a defensive player?
These three rules are technically all a offensive lineman needs to know to get the right block down. Being designated as either a play-side or weak-side blocker dictates what type of block you will be doing.
Suppose the run play is a wide stretch run towards the right side, and you're the left tackle on the play. It doesn't really make sense for you to block the left defensive end right? So as a weak-side blocker on the play, you're most likely going to help the left guard with his block before bouncing off to where the linebacker is. The overarching goal should be to reach the second level.
On the other hand, if you're the right tackle on that play, chances are you're going to start the point of attack - meaning, there won't be any play if you don't touch a defensive lineman. So as a play-side blocker, you're expected to win against the people lined up around you. You need to move the line of scrimmage forward, and anything else will probably result in a loss of yards.
Next, we move on to the covered or not covered aspect. Here, I'll allow Alex Gibbs, the architect of this scheme, to explain himself:
"If you are UNCOVERED, zone with your teammate to the playside. If you are COVERED, look at your backside (away from playside) teammate. If he is COVERED, you will block your defender man-on-man. If he is UNCOVERED, he will double team/combo block with you towards the LB.
Let's quickly refresh ourselves on the first scenario - a stretch run towards the right. We'll highlight the left guard, James Carpenter, and the right tackle, Breno Giacomini here.
As you can see, Carpenter is covered because the defensive tackle is lined up on his inside shoulder. Since he is covered, he has to look towards his backside teammate to know what he has to do. In this case, backside means left side, so he will see if Russell Okung, the left tackle, is covered. The defensive end is lined up towards Okung's playside shoulder too, which means Okung is covered. In turn, Carpenter will have to zone the defender himself.
Now on the right side, we have the second scenario with Giacomini, who has no one lined up in front of him or inside him on his right shoulder. He is uncovered. He gets the simple job of "zoning with his teammate towards the playside", or the right side in this case.
But, you ask yourself, which teammate does he double team with? Miller, the tight end, or Sweezy, the right guard? Either would seem to be a logical choice, but let's walk this through. The OLB lined up in front of Miller is on his outside shoulder (right side), which means if the hole was to open up in between Giacomini and Miller, the latter already has leverage in kicking the Bronco defender out.
Meanwhile, Sweezy has the trouble of having to reach across a entire lineman's width just to get a lick on an orange jersey, and if the DT was stunting right towards Giacomini, there will be penetration and zero run to begin with. The only decision left is for Giacomini to zone with Sweezy, which means he will double team with him until Sweezy manages to turn the guy away from the play. Then he will go to town on the first Broncos jersey he sees.
Cool, now you know what the design is. Let's see it happen in real time...
Now notice in the last frame here when Sweezy and Giacomini split off their blocks, it is Giacomini that ends up taking on the defensive tackle, and Sweezy on the linebacker. Does this seem to break the rules/design we set up from above? Possibly, but consider where the play is and the position of the linebacker himself relative to that. It doesn't make sense for Giacomini to go off his block and go all the way across his body to block him. So instead of Giacomini coming off, Sweezy switches their roles and he goes off in the 2nd level, while Giacomini keeps up with driving the defensive tackle as far as way as possible.
This flexibility is hard to come by with any football scheme, especially ones as tough to grasp as this. But it works because the rules only dictate the blocks you will make, now how you do it. The gist is this: Player X and player Y on the line are in charge of blocking this defensive tackle and this linebacker. And that's it - which brings us to our next section, which focuses on how these linemen actually make their blocks.
Steel34D from Behind the Steel Curtain did a great job in explaining the different type of combo blocks with his article, which I will post excerpts of it here. Keep in mind that while the terminology may be different, the core concepts are still the same:
ACE is generally the call for a combination block between the guard and the center. It is usually dependent on the defensive lineman. Generally if the D-linemen step towards the center he is the center responsibility the guard will chip and go to the second level. If he steps into the guard the center will chip, go to the second level and let the guard take the lineman. The guard will make the call. LION is the call for a combination block with the left guard and RAM is the call for the combination block between the right guard and center the center will specify the side to let the other blocker know.
Deuce is generally the call for a combination of the playside tackle and guard. Once again it is dependent on the defensive lineman and the direction he goes. The tackle will make the call at the line but only if the playside guard is free with no one lined up in front of him.
Trey is a combination block between the playside tackle and TE. It is called by the TE but only against a seven technique. This block is rarely used since the defensive end is rarely in the seven technique on the strongside.
Base is the call made by any lineman that is covered and the teammate inside him is also covered. The blocker will take a zone step and turn his body parallel to the runners' path.
It is vital that a successful ZBS mixes up all these different types of blocks, and use them with variant effectiveness. In the play above, we see Okung and Caprenter BASE block with their respective defender, while Sweezy and Giacomini combined with a DEUCE block. But unlike regular blocking schemes, these blocks are again previously employed by the three rules from above, which is why Sweezy and Giacomini switch their respective men in the play with regards to what was actually designed. Simply put, the rules dictate who you'll block, and you and your teammate(s) decide how to do it from there.
Let's take a look at another play. This is a run designed to go towards the left side that ended up for a seven yard gain right down the middle. We'll start again by applying the first two rules - defining where is playside (your right, offense's left) and where the weakside is (your left, offense's right), then seeing who is covered and who is uncovered.
From here, we'll apply the the last rule to each individual player to determine the blocks. Here is the view from the strong-side of the line:
So as you can see here, the four men on the right side (Miller, Bailey, Giacomini, Sweezy) have to tackle three Niners defenders - the defensive end in front of Miller, the defensive tackle in front of Giacomini, and the linebacker in front of Sweezy. Miller, being the last guy on the line, will be in charge of the defensive end one-on-one (as will Giacomini with the defensive tackle). Bailey, whose job is to "zone towards the playside" and the area, or zone I pointed out above. This will most likely coincide on the double team with Giacomini on the defensive end. The same will be said with Sweezy and the defensive tackle/linebacker.
These rules now set up the different types of blocks that Steel34D has most graciously provide. Bailey and Giacomini will most likely setup a DEUCE block, where one will take care of the DE and the other the safety about to crash down on the play. Sweezy and Unger will make a ACE block, again entirely dependent on where the DT goes - if the later moves towards the playside, then it would be nearly impossible for Sweezy to help turn his shoulder around.
Here's what happens on the first step:
As you can see, the only double team that really happens is between Bailey and Miller at the far left. Which seems to contradict what Giacomini expects from his block, predetermined by the three rules. Giacomini is covered and Bailey is not, which means he's expected to double team the DT towards the LB.
However, note that the double team doesn't happen straightforward at the point of attack. Giacomini will expect some help, but not right when the ball is snapped. If Giacomini could even manage to get across the DE's face without Bailey's help, than the combo block is called off and what we have instead is a BASE block - Giacomini takes care of the DT, Bailey with the LB.
The same happens with Unger and Sweezy. The DT slants hard towards the playside which eliminates Sweezy out of the picture, so all he has to do is move directly to the second level and get the LB. This is what I mean when I say that the ZBS is very flexible in terms of blocking. The offensive linemen plan and react at the same time as the play is developed.
Now that you understand the fundamentals of the ZBS, we'll continue on in the next part by explaining the bigger picture - namely, the difference between an inside and outside zone, and how the running back finally makes everything we talk about here worthwhile.