The Plays: Iso

The Iso is the core play you need to learn to run first and run often.  It is your staple inside run which will set up all of the outside runs for long yardage.  From the Shakin the Southland blog:

Why is it called the ISO? Its simple, the FB is isolated on a Linebacker or SS with a one-on-one block, leading the RB, who then cuts to either side of the blocker. It is sometimes called a "blast" play, but I have always heard that referred to more as an outside Iso. Its not designed to break long runs, because you're basically going right into the meat of the defense between the tackles. Its goal is consistent 3-4 yard runs, and by the 4th quarter, those will start to be 7-10 yard chunks.

This is why the play is sometimes called BOB.  In the play discussed by Andy Barall on The Fifth Down N.Y. Giants blog, "BOB stands for “back on backer,” and refers to the isolation block by the fullback on the weakside linebacker."  Barall links to a great video analysis of "36 BOB" run by the Giants against the Lions by Mike Mayock at the 1:30 mark. Barall: "The fullback, Bear Pascoe, had the isolation block on the weakside linebacker, Ashlee Palmer. The play is designed to isolate the linebacker so the fullback can block him one-on-one."

It is such a basic play that teams will work in all kinds of small variations on it.  The Giants ran that play with the WR in motion.  Some teams run the Iso play with a TE in motion.  What we will run is the standard no-motion Iso play from the I.

How the Play Works

What we have is a play designed to open a hole off the play side OG for the FB to lead the HB through.  The offensive line (and TE) engage in man/gap blocks to occupy the defenders, leaving the one linebacker with no help in a one on one matchup against the FB.  The blocking is intended to open a hole in the same place every time for the HB to hit and make a read off the lead block.

Here is Iso left against Miami lined up in a balanced 4-3 defense.  The linebacker who we are isolating is outlined in red:

At the handoff, let's see how the play has unfolded.  We have two combo blocks on the frontside, and our isolated LB is moving out into flat zone coverage.  The FB sticks with him and nails him as he tries to come back into the play.  Off the combo blocks, the LG peels off and takes on the MLB while the LT peels off the outside combo block to move up against the SS.

The play goes for a nice long gain - one broken tackle and it's off to the races:



Here is an Iso right play against Georgia Tech that we used earlier.  The blocking has a combo block to the inside and as usual we have the FB isolated on the linebacker set back over the hole.  The SOLB is lined up on the line in front of the TE, who will drive block him.

As the play develops, the nice inside hole opens up and our FB has a clear one on one block against the linebacker:

Back on Backer - the fullback executes his block just long enough for the ballcarrier to squeeze past. The HB makes the appropriate cut to the inside away from the SS help, and we break it for long yardage.



Bouncing the Play to the Outside

Sometimes, that nice hole will not open up for the FB to lead the play through.  If the defense can clog the running lanes with enough defenders, there will be nowhere to cut and the play will stall behind a massed pileup at the line of scrimmage.  If the defense takes away the inside holes, though, chances are containment on the perimeter will be weak.

Let's look at an Iso right play where the defense has good inside help and lots of defenders in the box.  This is typical as you get nearer to the end zone since the defense does not need to keep to keep depth against long passes; so the safeties are closer up near the line.  Georgia Tech here has lots on the back side of the play, which will flow to the run quickly once it is diagnosed:

The wide gap in the defense is directly over the RG, which will tend to push the play further to the inside since that is where the natural hole is likely to appear.  In fact, this is exactly what happens, with most of the space at the center of the line, with several defenders on the back side unblocked and ready to attack the center of the formation:

You can see three free defenders on the back side and the play side is very cramped.  If the FB goes through the hole and blocks the free LB, there is no room to cut around him.  The HB is trapped if he stays inside, and will get caught by the defenders pursuing from behind.

Notice there is not much help on the outside.  Since the defense has taken away the inside, we can glance at the outside and see if there is an opportunity for bouncing the play to the edge.



Sometimes it will be obvious that the defense is overcommitting to the inside. That's when you exploit them by going around:



Here's Navy's weak side heavy defensive alignment:



Look how there is just no deep help on the strong side:


One last example, showing another defensive set where the right end of the offensive line (the TE) is positioned to the outside of the last edge defender.  This makes it much easier for the line to hold the corner for an outside run to get around.  Here Clemson is in a goal line set trying to stop a 4th and 1 conversion: