Split Field Coverage Concept - The Underneath Players

What's underneath there???

I get a lot of questions about this topic, especially regarding TCU's Blue coverage and how they deal with crossers.  Now, I've not heard it from the man himself, but from what I've watched on film and broken down, here is what I've come to find out.  To first illustrate, we need to look at how traditional zone coverages, that are not split field in nature deal with crossing routes.

Traditional Zone
In a traditional zone, much like in basketball, routes get passed off to other defenders when the run through a zone.  In the early years, if you were to have run with the receiver after he passed through your zone, you surely were getting yelled at as a player.  The idea behind zone is that all eyes are on the football and that in an attempt to minimize spacing, you pass routes off to one another.  This works good in basketball where things work on a much tighter scale, however in football, OC's found out that there was just too much ground for a traditional zone player to have to work with to effectively control passing concepts by simply passing one receiver from zone to zone. This "passing off" is where many zone coverages fail and it's for two major reasons.  Reason one, is sheer athleticism.  Most underneath zone guys are linebackers or inverted safeties who are not as fleet of foot as their cornerback counterparts, yet they are still having to cover receivers within their zones.  As the spread has evolved, instead of the number two receiver being a tight end or a running back, he's now a slot receiver, which makes this match up that more lopsided in the offenses favor.  Secondly as offenses have advanced through the years, passing concepts have become more and more advanced, and are using this "passing off" technique against the defense by overloading zones with multiple crossers and/or high lowing a zone AND adding a crosser.  These two factors are the single most important reason to pattern read in my opinion.  That's for another post however...

Anyhow, in traditional zone, if a hook to curl defender expands to his landmark and gets a receiver coming into his zone, he runs with him, until something makes him stop.  Now this can be the edge of zone, or another receiver entering his zone.  A lot of people call this passing the route and looking for work.  In the beginning of pure zone coverage concepts, I'm sure this was the bees knees, however as offenses have figured this out, the stress put on these underneath coverage guys by both horizontal and vertical stretches have become so great, most folks are not using any "pure zone" concepts anymore (if you are, please proceed to the nearest mental hospital, put on one of their fancy white coats and stay awhile).  With two speedy receivers crossing in a linebackers zone, or high-lowing his zone, the idea that you ask him to split the two and rally was a good answer in the beginning, but as QB coaching has progressed, even in high school football there are kids who can fit the ball into the tightest of windows.  So now you get pattern reading.  But how does pattern reading and the split field concept tie together?  Let's take a look.

Reading...you're doing it wrong!

Pattern Reading
I would venture a guess that ALL major college football defenses pattern read.  I'm sure there are a few that still use some landmark drops, but most are now at least using a progression type read, reading from two to one, or one to two and so on.  Other pattern read schemes have very definitive rules, such as "all of number two vertical and out", which gives a clear cut picture of what the defender is doing.  This pattern match principle can be easily seen on display every Saturday afternoon in the fall.  Pattern matching is not really all that new either, but it's refinement is what's really taking pattern matching to new heights here lately.  Anyhow, what I really like about pattern matching is the definitive answer to reacting to what a receiver or offensive player is doing.  This leaves very little gray area for the defender to have to deal with.  Gray areas are what force your players to play slow, because it makes them think. Now many of those that argue against pattern matching, don't really understand the concept and just how concrete it is.  It's the best of both worlds is what it really is.  It's zone in nature, which means we have all 11 eyes on the football at the snap of the football, helping immensely with stopping our opponent's run game.  Secondly it's man in nature in that once the man trigger has been pulled by the defender, he simply covers the receiver man to man.  We all know that man is one of the simplest coverages out there, so all you are really doing, when pattern reading, is giving qualifiers to man coverage.  Anyhow, I could go on for days here, but even in pattern matching, defenders can still pass off routes to other defenders.  In Saban's Mable adjustment to trips, if there are two crossers, the inside linebackers will pass them off to one another, they do not run with them man necessarily, even though their base rule would say to do so.  This can lead to some confusion though and lead to open receivers.  It can also allow the offense to use this passing off feature against the defense, much like offenses exploited it back when it was still a pure zone concept.  So how does the split field concept alleviate the stress put on a defense by crossing receivers?

Split Field and Crossing Receivers
Now I'm speaking of how TCU's split field concept works and what makes it so solid, I'm sure there's plenty of split field coaches out there that will disagree with this approach, however the TCU scheme is by far the BEST I've seen for dealing with crossing routes.  Let's set up a two-by-two set up playing Blue to both sides (though TCU does not do this, we could simply say playing quarters to both side etc.).  Anyhow, does not matter where the read side is, just keep in mind what the underneath players are doing.  Let's look at the following concept (similar to the levels concept) out of the two-by-two formation shown below.

The corner to the away side has to honor the vertical of one to help the weak safety get over the top, so the out will inevitably be open, however the Mike, is the slice player so he will exit 90 degrees in an attempt to undercut this route.  Now, if the read side linebacker (Sam in my illustration), passes off the shallow crosser, the QB can have a field day!  Here's where the man trigger of pattern matching comes into place.

As we can see from the illustrations, if the read side linebacker passes the crosser off, there's a large void and an open area for that receiver to sit down in.  If he runs with the crosser, which he should, then this window is immediately closed.  Also, from the illustrations, you can see there are still elements of pure zone coverage as look at the strong safety, who sees two go inside and knows now I look to work under number one's route.  He is, in effect, "passing off" the crosser to the inside linebacker, which as stated above, is a pure zone concept.

Now, the other beauty of the way TCU plays things, is that behind everything they do, there is a "common sense rule".  Which basically means, "don't do anything stupid".  For instance, one would say, "What about mesh coach?".  This is a valid question, since now you have two crossers and as we all know (or should know), crossers can severely damage man coverage, ESPECIALLY when they cross.  Here's where the common sense rule comes into play though.

The two linebackers will communicate to each other on the crossing routes and come off and switch.  Here the switch makes sense because Mesh attempts to beat the tar out of man coverage with these crossing routes.  Had the two defenders stayed locked in man a natural rub would occur and one defender, or both, could be compromised, thereby leaving a receiver open.

The Weakness
Much of the questions I get on the subject of underneath coverage defenders has to do when one of these defenders is assigned to the vertical of a certain position.  For instance, in Blue, the read side linebacker is the middle hook dropper and will have all of number three vertical.  This scares the hell out of folks, because they are not accustomed to having their linebacker run with any vertical threat.  This is not a big deal IF you've done your scouting homework.  I once faced an OC in that would get in stacked twins, two-by-two look with the receivers out on the top of the numbers and would run the running back vertical down the seam because he knew we were running quarters.  They had a major down and distance tendency for doing this, and had a damn good running back who could catch as good as any receiver on their team.  When we saw this look, or expected it, we simply rolled into good ol' country cover 3.  They ran fade/hitch with the other receivers which cover 3 took care of nicely.  The safety would roll to the MOF and we ended up picking off that route once and breaking up another to where they quit running it.  My point is, don't make one coverage fit everything.  That would be like you waking up in the morning, trying to find an outfit for the office that would also look good for your job interview that afternoon and be comfortable enough at your son's Little League game later than night.  CHANGE YOUR FRICKEN' CLOTHES DUDE!!!  C'mon, don't ask one coverage to cover everything, I mean that's what everybody supposedly loves about cover 3 is that it aligns to everything.  BIG DEAL, it covers NOTHING, so why use it?  If you know a team likes to do a particularly thing you need to have an answer for that.  It may mean another coverage, it may mean tweaking what you have, but Lord knows, whatever you do, don't just "hope" your linebacker can run with their back if he can't.

We have found a weakness!

The other thing I get, is coaches saying "Well that's just man, I don't like my linebackers to play man".  Well why not?  I mean, the best way to see man to man coverage, is to go to a playground and watch kids playing tag or a pickup game of football.  If you watch, there will be mismatches everywhere, hell that's LIFE.  But watch closely and time up the time that the kids begin to run or chase the other kid and the time that one either separates or closes the gap between the other.  You will see this time will be around three to five seconds.  Sound familiar?  Any kid can run with a receiver for three to five seconds, anywhere on the field.  This is not a major issue in my book, and I always roll my eyes at that question, but go check it out for yourself.  The other thing to remember is that 75 percent of pass defense is pass rush.  So if your guys can run with their guys for three to five seconds, you need to be able to apply pressure in that same amount of time.  That, my friends is EXACTLY how good pass defense works.

The face of your pass defense.

To me, the major weakness of the underneath coverage in the split field concept is communication.  If communication is missed it can lead to open receivers or defenders running into each other.  It is imperative that you, as the coach, make sure that your players know not only why they should communicate, but how to effectively communicate.  I worked for a guy that used to have underneath guys yell "crosser" when a receiver would cross in front of them and leave their zone.  I always wondered why, because trying saying the word "crosser" with a mouthpiece in.  I came to him one day, and said "Why don't we just say in, instead of crosser?  It's shorter and easier to say than crosser."  He looked at me, as though he'd never thought of that, which to find out, he hadn't and we immediately changed that and our communication with our underneath players got much better.  These are the things that you, the coach, can do to facilitate your players and help them be successful implementing the underneath coverage in a pattern read scheme.

Conclusion
The underneath coverage  in the split field concept is not as tricky as folks make it out to be, especially if you build communication into your system and a set of fail-safe rules.  I always tell folks, using the word "always" in building your rules is a bad thing, because good OC's find out your "always" and then exploit it.  Keep your rules open and flexible as possible to allow for your players to adapt to what they are seeing.  Just as in the example above, both the inside linebacker's man keys were triggered, but because of communication and common sense (which should be ingrained in how you coach the coverage to your players) these players knew what was coming and were able to adjust.

Always...not "always" a good word...

Duece