In 1823, during a spirited kicking-style game, a young man named William Webb Ellis picks up the partially deflated pig's bladder that they are using for a ball, and with time running out carries it across the goalline for the winning score. This is, of course, against the rules, which strictly prohibits touching the "ball" with your hands. And the score is, of course, disallowed, since if you can't touch the ball with your hands you most certainly can't carry it anywhere.
Which isn't to say that it isn't a good idea. It was. And is.
That this was done at the Rugby school, in Rugby, England, should come as no surprise. "Running the ball" had entered the conversation, and now 191 years later, ask any NFL coach where his defensive gameplan starts, and he will tell you, "with stopping the run."
Stopping the Run. A defense's first and foremost task. And it is no different with the Under defense that we are dissecting here. Every day, every play the defense, from linemen to defensive backs, lines up and their first read is to stop the run. Their keys revolve around reading the run action. They fire off the line expecting run. And if they are successful against the run, then everything else can fall into place.
The Defensive Line
In the typical 3-4 defense, the nose is a behemoth, affectionately referred to as a 'war-daddy.' In the 4-3 Over, the tackles originally two-gapped. Hybrid defenses which sought to create mismatches on the defensive line would pursue hybrid players, 'tweeners' who could be coached at two different positions. These defenses and many more share a common, and wholly expected, characteristic in that tackles required 'tackle coaching,' ends required 'end coaching,' and the rarest of all, a true nosetackle required 'nosetackle coaching.'
Different positions, different somatotypes, different players, different coaching. All these differences have been a part of designing and installing defenses from the beginning, requiring lots of time in the classroom and in drills to get players up to speed on roles and responsibilities along the line.
The Under defense changed that paradigm.
You'll remember from Part One that the Under defense is fundamentally just a defensive line shift of two players, the interior defensive linemen, but that this simple shift sets off a chain reaction throughout the defense that, once adjusted to, creates a terrific run-stopping front that couples to a myriad of coverage shells effortlessly. An additional benefit of this shift, is that it puts every defensive linemen--the nose, ends, tackle (and even Sam linebacker though he is NOT considered a part of the defensive line for purposes of installing and teaching the defense)--into an "outside shade" position versus an offensive blocker.
The diagram shows which side of a blocker the DL is aligned over. "Outside shade" refers to lining up on the outside of the blocker, and in the Under, ALL linemen are lined up to an outside shade. In fact, most of the time the linebackers and Rover (typically called a 'strong' safety) are in an outside shade technique on their charges as well, such as the Sam outside the TE and the Will outside the RB. In military tactics, such a concept would be called "flanking," and in football the effect is to shut down outside runs before they can even get started. This idea of outside leverage is so intertwined into the Under that most coaches who embrace the Under front embrace the concept of outside leverage as well, applying it all the way through to the secondary. This is the Big Picture of Outside Leverage with the Under defense.
But on a more microscopic level, in the trenches where outside leverage amounts to little more than an inch or two of space and milliseconds of time, defensive linemen gain an unexpected benefit from this outside technique: all the linemen see identical blocks.
What this means (and without getting into a lengthy primer on offensive blocking techniques) is that if you are lined up over the weakside guard as a tackle you will only see a particular handful of block-types, and these blocks can only be executed in a limited manner. If you then line up as the strongside end by the Sam, you will still see only those same blocks executed the same way. This makes the base much quicker to install, since it only requires one set of coaching principles and one set of drills. It also simplifies the "basics" for the linemen, which leads to quicker contributions from young players and free agents. But where it really shines is in what it does to the "positional requirements" along the DL.
It makes the defensive linemen completely interchangeable.
The benefits of this cannot be understated. You say you want a multiple front capable of varied looks? How about being able to flip flop the tackles or ends at will? Want to keep your defensive line fresh throughout the game? In the Under you can rotate out anyone for a breather without changing alignment or assignment. Have a particular matchup against a specific offensive lineman that could blow their blocking scheme wide open? Feel free to install any particular matchup into the gameplan without any extra work required. Worried about carrying enough depth at an injured position on gameday? Rest assured that you only need to activate five DL on the 46 man roster, as one replacement can play all the spots.
For the Broncos, they prefer not to 'hybridize' their linemen (i.e. bigger, heavier players rarely leave the interior and faster players usually stay on the ends) and they prefer to carry 3 extra linemen on gameday when they can, one true interior player, one true end and one "5th"' DL, or player who can line up anywhere. In recent years this "5th DL" has been Malik Jackson, who, like Wolfe, has a faster, larger frame that is well suited to moving along the line in relief. Of course, he isn't limited to that role, since the versatility of the front will allow him to matriculate as far as his talent and willpower can take him at whatever spot on the DL needs him most, as his starts at the strongside end position indicated at the end of last year. And when that happens, the Under front's simplicity will allow a younger or newer player to quickly step up and fill the role Malik leaves behind.
Defensive Line Specifics
When he is aligning, the lineman will crowd the line as much as possible, since he is trying to line up as close to the ball as he can manage while still remaining in his outside shade alignment. The sooner he engages the blocker in front of him, the sooner he annihilates the block and makes a big play. His typical stance will be with his hand closest to the ball down, and his foot closest to the ball back. This stance allows him to see his first key, which for DL is always the ball. Typically his feet will be shoulder width apart with his back-foot toe lining up with the instep of his front foot, however, in obvious passing situations Del Rio might loosen up and let his guys line up with a narrower, but more elongated stance to better get up field after the QB.
We already know from Part One that the Nose will be lined up as a 1 or just "shade" technique (meaning he is shaded towards the strongside guard, but covering the Center), and that the Tackle will be in a 3 technique over the weakside guard. Additionally the End will be in a 5 technique on the strongside while the Bandit will be in a 5 technique on the weakside. Note in the below diagram that the End and the Tackle both have a gap to their outside that is covered by another player on the line.
Whenever this occurs to a defensive lineman (the gap outside of his own covered by a player at the line) he is allowed to switch his technique to a "heavy" technique (indicated above by the extra line on the blocker. "Heavy" simply means that he will align with his inside foot lined up to the center of the blocker, rather than with the blocker's outside foot which is standard.
Reading The Blocks
As to the blocks themselves, a DL is taught to first key on the ball (i.e. watch the ball to see the snap) and then fire off the line expecting a running play. DL in the Under will see either drive blocks (ISO type plays) or reach blocks (zone and outside runs) and will only see double-team blocks from the outside.
In all cases, his second key is the V of the neck of the blocker directly over him. If that V goes straight forward it is a drive block, and the defensive lineman should drive forward and at least maintain the line of scrimmage, locking out his arms to shed the block down and away from him. If the V moves to his outside, the defensive lineman is recognizing a reach block, where the blocker is trying to outflank him to the outside. Now the goal of the defensive lineman is to control that blocker by keeping his outside arm on the outside of the blocker. Note that his goal is not to shed, and in the NFL that is rarely going to be possible anyways. He is essentially playing the role of a two-gapper, by controlling the lineman, while the linebackers will read this to make a play on the ball in his assigned gap. Note that this only works because of the "tandems" concept we discussed in part one, where the proximity of the two outside defenders in the Under effectively prevent any team from executing two outside reach blocks. Also note that all double team blocks will start out as drive blocks, and as we already mentioned, the extra blocker will ALWAYS come from the defenders outside shoulder. They are played the same as drive blocks, except that once the extra pressure is felt, the defender may need to leave his feet in an effort to twist the first blocker into the extra blocker. In the Under, double teams aren't "split" as is commonly heard. More typically they are absorbed as in the 3-4, with the defender absorbing two blocking assignments if he is successful, or what looks like a double team is actually just a chip or kickout block (or a pass block which isn't technically a double team even if it is two on one). It should also be noted that unless an offense commits two tightends to one side, the Sam linebacker cannot be double-teamed. He can be chipped by a RB, but a true double team is reserved for the linemen (and are terribly difficult to execute versus the Under anyways).
Of particular importance for the defensive lineman is correctly handling an inside release or "down block". Think of the pulling lineman on a Power-O play, or the trap play where the defender gets blindsided. If his key, the V of the blocker's neck moves inside, then the defender is recognizing a down block situation. The offensive lineman will release inside, and now the defender's goal is to step inside with him (called the "block down, step down" rule), hopefully getting his hands on him to push him down and toward the snap (which protects the linebackers), but due to the angle of departure of the offensive lineman this is often not possible. At this point the defender will either be kicked out (usually by a fullback or the pulling lineman) which indicates the play is coming toward him, or no one blocks him, which indicates a play away from him. On rare occasions there could also be some kind of option play.
If no blocker tries to kick him out, he should trail behind the inside releasing lineman looking to maintain his gap and prevent a cutback lane from forming, not penetrating too much or too little. If a kickout block does come, it is up to the defender to spill him.
Spilling is essentially splitting the blockers, though the inside releasing lineman isn't actually engaged with the defender. Whether it is a RB or pulling guard, the defender wants to drive his outside shoulder into the kickout blocker and get as far inside as he can. When he hits the kickout block he wants to get as low as he can and on the inside, so recognition is paramount (and should be easy if the defender is reading his key properly).
As you can see from the diagram below, if a defensive lineman executes properly vs an inside release with a trap block, then he will effectively switch gaps with the linebacker on his side. This is the first step in gap exchange, which we mentioned in Part One and which we will discuss more when we look at the linebackers.
Lastly, a defensive lineman in the Under will occasionally see "fan" blocks. No, this isn't when a Southstander gets bombed and streaks the field, it is when the offensive line blocks outward, generally in a fan shape.
This is a type of drive block popular with teams that run Isolation and Power It is for inside running teams who have the strength advantage. The offensive lineman drives out instead of forward with no reach step, in an attempt to force the defender even further outside. The defender's main goal in this case is keep his blocker constrained, and maintain his position along the line of scrimmage, neither driving into the backfield more than a yard, nor allowing the hole to widen. The danger here is that vertical as well as horizontal holes can get opened if the defender penetrates too far. This is similar to the principle of edge contain on passing plays where the Bandit and strongside End are responsible for not getting run past the QB.
With few adjustments and fewer keys to adjust to, defensive line play in the Under is the simplest component of stopping the run. It is also the most essential. Whether a defensive lineman records sacks, or tackles for loss is mere window dressing to his role as a block disrupter who keeps the defensive gap alignments sound and sets the linebackers up to make plays. But in the Under, the big boys are given plenty of opportunity to shine, with an upfield mentality focused on destroying blockers and forcing them to run "away" schemes from your best linemen. With the outside running game neutralized primarily by alignment, you can know that on any day where you are holding a team's inside running game in check, that the defensive line has done its share of the work.
Later we will look at line stunts and games and how they affect the base package and gap soundness (and why Denver chooses to use a 5 man line to accomplish many of the same goals as stunting does). However, in Part Three we will be looking at the Linebackers role in stopping the run, and how the defensive backs adjustment to the linebackers helps set the base coverage calls for the Under.