Defeating the Under Front Defense with the I Formation Offense

Let me start by saying, the Under front is a fantastic defense versus 21 personnel I formation teams.  They provide excellent leverage against on the outside. Let's start with the basics of the under front and why a defensive coordinator would utilize that against the I formation offense.

The under front presents an offense with a shaded nose to the strength, a 5 technique end outside shoulder on the tackle, and a outside linebacker or defensive end in a 9 technique on the tight end.  To the weakside you often see a 3 technique over the outside shoulder of the guard and a 5 technique outside linebacker or end outside shoulder on the tackle.  The weak inside linebacker sits in a 20 technique or a 20i technique, with the strongside inside linebacker sitting in a 30 technique normally. According to Jerry Gordon, author of the fantastic book entitled Coaching the Under Front Defense, the weakside inside linebacker in the 20 technique often needs to adjust his width to stay just outside of any fullback to ensure that the defense does not get outflanked.

Under Front Strengths:

• Only One True Bubble (Strongside B Gap)
• The Will (Weak Inside 20 tech) is protected by the defensive line
• A true 5 man front, can get 9 defenders in the box quickly
• Can Be played both aggressively and non-aggressively
• Capable of multiple coverages
• Tandem DL to prevent outside runs or off-tackle runs

Under Front Weaknesses:

• Limited Coverages to a nub tight end 
• Weakside A gap provides good angles
• Weakside safety can be manipulated with twins/slot looks
• Tight end trade
• Fullback motioning to a wing position next to the tight end

How to Attack the Under Front

You need to game plan what way is the simplest way to efficiently attack the Under front.  For instance, do you have time to install tight end trade or motion the fullback?  If you don't think that is worth your practice time, you should look at utilizing a twins formation.  Personally, I think the Under front does have two bubbles.  I believe the weakside A gap needs to be attacked constantly.  The Will linebacker in the 20 technique is someone who is often undersized.  This presents a solid matchup for potential fullbacks in the I formation.  In addition, the angles the shade to the strength and the weakside 3 technique defensive tackle offer great angles to attack the defense.  Therefore, since you can essentially neutralize two potential strengths of the under, it seems like a great place to attack.

In this example, we see how the weakside A gap can be attacked in a number of different ways from the I formation, using the Iso play and the Midline play. By using the I twins formation, a football coach can easily create a seam in the defense.  The coverage above is a cover 2 look, with the strongside corner playing the deep half and the sam linebacker playing the flat.

In you receive a lot of cover 2 looks, you should also run to the strongside.  If your tailback can make a defender miss, especially a cornerback, this presents big play opportunity.  The picture to the left doesn't illustrate this, since we are in an I formation pro look, but it does illustrate how the power play would indeed look.

A lot of Under fronts run Cover 4 or Cover 6 (Quarter Quarter Half) with the quarters being played to the 2 receiver side.  This presents a lot of 2x1 21 personnel teams problems because of an unblocked defender to the weakside.  Using the twins formation can control this player.

As the picture to the right indicates, we are probably getting a true cover 4 look, or a cover 2 "read" look where the corner reads the #2 receiver with the free safety and breaks to the flat if the #2 receiver does bubble or go flat from a slot position.  Here, the offense called a strongside iso play, but because the rover is in the box and the free safety is at a depth of near 10-12 yards, the bubble play is a great adjustment.  Even if they ran the original play and simply had the receiver run the bubble, it should control the rover allowing the tailback to pick up a few extra yards.  That is what football is all about.  Finding small adjustments to pick up 3 more yards on any given play.

But how can you control the Under front with the passing game?  Especially quarter quarter half teams.  I have spent a long time contemplating this.  Overall, I feel a read route by #2 running at a depth of approximately 10 yards is ideal.
The free safety will be in a bind because the depth of the Z receiver's route here.  The z receiver also needs to feel the leverage of the rover.  This play can be run from a play action look or a 5 step drop.  The box indicates the QB's primary read, in this case, the near safety.  The QB should identify his position immediately after the fake if it's a playaction.  If the safety jumps the read route, then the quarterback needs to look to the corner.  This is a big play opportunity for the QB. If the safety stays over the top, the QB should read the leverage of the Rover safety on the Z receiver running the read route and throw the ball the opposite way.  The tight end's goal here is to acquire the attention of the strongside half field player in order to clear room for the post.

Finally, this is a route combo I picked up from Coach Petrino, offensive coordinator at Illinois this weekend.  It's your tradition cover 4 beater, double posts and a wheel.  Except he added one more flat route whose goal is to be seen by the hook/curl or flat defender who typically would follow the wheel.  The wheel defender usually expects someone else there to pick up the wheel with the flat player's presence.  This settles his hips and allows the wheel to become wide open in the spot cleared by the double posts, which move the free safety and corner.  Protecting the QB would probably be the only issue.  The posts, according to Petrino, are not part of the read.  It's a high low read on the wheel and the back in the flat.  One of them will be open.

Overall, defeating the under front can be tricky.  However, with small preseason planned manauvers, a coach can setup their offensive side of the football for success.  Simply be patient and work the play action combo's when they are there.  Understand the coverages they play and take full advantage of them.

These are only some suggestions, but if you have more, please feel free to leave a comment.