Tuesday, July 26, 2011

Coverage: It’s Academic

Believe it or not, we’re entering the fifth season of this blog, though only getting the hang of it for the last three.  That being said, the next few posts will lean heavily on archived content so not to insult any of you readers by retreading previous topics.

As we’ve covered before,  remaining gap-sound in run-support is a fundamental equation that is addressed every snap based on the formation.  In this post, we’ll look to set a foundation of defensive concepts through fragmentation.  After setting this ground work, it will be followed with different alternative coverage adaptations available to a defense.

One of the biggest mistakes for those learning the game of football is to fixate on the minutiae of various “brands” of defense.  Tying oneself to the dogmatic thinking and going-through-the-motions of “how we’ve always done it” without understanding the rationale of how it all works creates an intelligence rut that becomes a liability.  Defenses exist to defense an offense – they do not exist within vacuums.  On every play you’re defending something the offense is doing to advance the ball.  For this reason, defenses aren’t static entities – they must respond (adapt) to the stimuli they are presented with.   You will hear people declare, “we are a 3-4 Quarters defense” or something to that effect.  That’s great, but there is a reason a defensive concept is employed on a given down, and there is no catch-all defense available.

"Exhibit A"
Belichick on Defense

“At the Browns we played a 4-3,” Belichick said. “We won two Super Bowls playing a 4-3. In ’01 and (‘04). Second half of the ’01 season, we played 4-3 after Bryan Cox and (Ted) Johnson got hurt.”
“In all honesty, most people thought we played a 4-3 at the Giants,” Belichick said.

“Lawrence Taylor did a lot more rushing than he did pass dropping. He was probably 90 percent of the time, 80 to 90 percent of the time he was the rusher in the defense. Now not every play was a pass, but certainly in passing situations and on a lot of pass plays, he was the designated fourth rusher which really put us in what amounts to a 4-3. I think honestly that’s somethingthat’s a media fabrication. There are a lot of different alignments out there, you see 4-3 teams use odd spacing, you see 3-4 teams use even spacing.”

“Look, you have 11 players,” Belichick continued. “You can put them in various positions. Whether you want to put it in the pregame depth chart as one thing or another I think is a little bit overrated. You play different fronts, you play different spacings and you teach the techniques of your defense and that is what is consistent. The techniques that are taught in the different defensive systems, whichever one you want to talk about, are consistent within those systems.

A defense really just needs to be concerned about offensive numbers (and how to match them) and the offensive capabilities from their alignment.

While touched on a while ago with TCU’s split-field philosophy,  the divorcing of the secondary from the front minimizes the detail of checks a defense would need to concern itself with as well as compartmentalizing the teaching method for each player position.  While coverage and front remain related by arithmetic, they can become independent of one another and still function together seamlessly.

its nothing but numbers

First things first is to match the front.  In every offensive formation you will have 5 offensive linemen, creating 6 gaps for an offense to attack.  The defense should have a plan to account for these 6 gaps presented, typically with 6 defenders (i.e. “the box”).  If we (continue to) use the 42 Nickel as a base concept (all of this remains true if you’re a 4-3, 3-4, 33, 50, etc), your bare minimum in the box will be 6 defenders that won’t ever have a reason to “break” their alignment because they ARE the box (they are the minimum gaps being defensed).
As more offensive players are introduced into the box, they create additional areas of attack through leverage (gaps).  The defense will fundamentally respond by adding more defenders to this area or risk being out-numbered at the point of attack.


Adding an additional back or tight end to the formation creates even more running lanes, necessitating yet another defender into the box to compensate.

All of this becomes a very academic application that generally gives you a clue as to what and how an offense is trying to set up its next play;
  • if you get 1-back you’ll have 7 gaps
  • if you get 2-back you’ll have 8 gaps
It also lays a conceptual ‘budget’ for the coordinator.  If you get X personnel grouping, you need to respond with Y defensive package and anticipate a limited selection of attacks.

After addressing the numbers in the box, you will have to figure out what you’re going to do with those other guys left in the secondary.   For the remainder of this post (and subsequent posts), we will ignore the box defenders and fragment our discussion into the leftovers of the formation.
With 1-back, we’ll have 2x2 (4 immediate vertical threats) and 5 defenders to match them. image
With 2-back, we’ll have 3 immediate vertical threats with (essentially) 4 defenders to compensate.  With 2-back (or 3x1), you can get away with doing some flexible things to the single-split side without carrying tremendous risk.

Like we discussed in the earlier TCU 2-Read post, we’re going to narrow our focus on the 3-on-2 matchup to the slot receiver side.  When the defense is presented with two split receivers it faces an immediate horizontal stretch (away from the box) while being threatened with a vertical / levels attack.
Fortunately, because of the numbers advantage, there are several ways to play this set between these three defenders (with each having distinct advantages).  Keep in mind, the variations listed below could plug-and-play any one of these defenders into a role (hence the multiplicity in how slot is treated).

You could feature 1 underneath force player and 2 deep coverage defenders (sky, cloud,  buzz).  This could be country Cover 3, quarter-halves, or bracket coverage on the #1 receiver. image_thumb5
You could have 1 deep defender over the top of 2 underneath defenders.  This could be anything such as traditional Cover 2, robber or bracket coverage on #2. image_thumb6
Or have 1 deep defender with 1 underneath (seam) defender that could be Quarters (Meg) or fire zone. image_thumb7

Or it could simply be man-under coverage with deep help. image_thumb8
All of these alternatives can be played from one defensive (presnap) alignment, yet create a world of hurt if an offense filtered their throws through defender reads.

A feature of this exposition should be to illustrate how "what TCU does" (in the secondary) is actually what every other defense (NCAA/NFL) does - they both end up in the same scheme when its all said and done.  With TCU's patented "3 coverages", you end up with a combination of 9 coverages available (2, Blue, 5, 25, 2 Blue, Blue 5, Blue 2, 5 Blue, 52).  All of this is a result of how the slot is played.  Whether you are the Horned Frogs, the New York Giants, or the San Diego State Aztecs.....whatever scheme you call yourself playing; you arrive at the same destination.

With this preface set, in the next few posts we will discuss the many different slot coverage adaptations available to a defensive coordinator.  We’ll explore how they work within the overall scheme, why it is advantageous to not only treat slot sets differently, but also how to effectively keep quarterbacks guessing when confronted with all the variations the defense can give them.

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