Saturday, November 21, 2015

4-2-5 Basics: Run Fits vs. 2 Back Formations

People often ask me about how we fit the run in the 4-2-5. They say things like:

"4-2-5 is just a 4-4 with DB's at OLB, so you just fit the run like a 4-4?" or
"4-2-5 is just a 4-3 using nickel sub personnel on every play, so you fit like the 4-3?"

My answer is "Yes" to both. Part of the reason the 4-2-5 is popular is that it can fit the run like a 4-4 or like 4-3. Teams can tailor the fits to their needs. Take for example a basic two back 21 personnel pro formation.

The defense can align and fit the run like a 4-4. The SS and WS play force while the four down linemen and two inside linebackers account for all the interior gaps. 


The defense can choose to fit the run like a 4-3 with a safety filling the role of the third linebacker.

In this example the defense bumps the linebackers (Mike & Will) strong and bumps the WS into the box in the role of the third linebacker. Against a strong or weak flow running play the Mike, Will, and WS fit the run like a Sam, Mike, and Will in a traditional 4-3 defense would fit.

Versus a strong flow run

Versus a weak flow run

The defense can alternatively choose to bump the SS into the box and the linebackers weak. The SS, Mike, and Will then fill the role of the three linebackers.

Versus a strong flow run

Versus a weak flow run

Lastly, the defense can drop the FS down into the box to fill the third linebacker role.

Versus a strong flow run

Versus a weak flow run

How can a defense use this multiplicity? 

Take for example:

Here is a standard Iso or Lead play from a 21 personnel Pro I formation. If the defense chooses to fit this play like a traditional 4-4 defense, it can become a stress play.

In this scenario the Mike LB fit the FB on the outside half. If the inside linebackers are expected to bracket the fullback, the Will has a difficult job. The Will needs to align wide enough to keep leverage on the guard in case the offense is running an outside flow run weak, like outside zone. This prevents the Will from cheating his alignment too far inside. The result is the Center and Guard can scoop the Nose up the Will, potentially cutting the Will off from his bracket responsibility. 

One alternative solution is to have the Mike spill the fullback.

The Will LB's job is easier because he doesn't have to bracket the FB with the Mike. The new challenge is if the Mike is fitting inside of the fullback's block, who is fitting outside? The offense has a good angle to use the TE to block the SS from folding into the box. That leaves the FS. The FS can make the tackle but not without issues. The RB vs. FS may be a bad match up.  The FS may have to make an open field tackle vs. a full speed RB. Requiring the FS to be hyper aggressive to fit the run also opens up play action risks.

Neither fitting the Mike inside nor outside of the fullback may be optimal for the defense.

Some coaches may say:
"The DT needs to squeeze the guard's block and reduce the A gap."
"The Nose needs to control the scoop block, keeping the offensive lineman on the line of scrimmage longer. That buys time for the Will."
"The Mike needs to be violent and jam the fullback back in the hole."
"The Will needs to read his key and be quick to attack the ISO."

These are all true. The issue is that may be easier said then done. Especially when playing good teams. If you want to compete for conference and post-season titles you are going to have to play and beat good teams. What is the solution when their fullback is better than your Mike? What if the guard is getting movement on the DT consistently? Being able to change how the defense fits the run can help give the defense solutions to these problems.

Here the defense bumped the linebackers strong and is using the WS as the third LB.

With the Will bumped over the Center the Mike and Will have much easier time bracketing the fullback's block. The offense does not have an easy angle to block the Mike or Will.

More examples:

When the offense is using an offset fullback or an unbalanced set, the defense can sure up run fits by bumping to a 4-3 run fit.

Having the linebackers bumped can help get players to the point of attack. The offense most likely wants to run toward the offset fullback. It makes sense to get extra defenders where the offense wants to run the ball.

Here is an unbalanced formation. The offense most likely wants to run toward the unbalanced side. Being able to bump to a 4-3 run fit can help the defense remain gap sound even against the extra gaps created by the unbalanced formation. TCU coach Gary Patterson wrote about the concept of bumping in the 4-2-5 in his article for Nike Coach of the Year. On pages 6,7,8 of the article Coach Patterson explains TCU's slide and scoot concepts. 

There are other times when the defense wants to fit like a 4-4.

Here the defense is in a 4-3 run fit. If the offense is running a read power to the weak side the defense may have difficulty. The WS has a poor angle to force the wide path of the lead blocker. If the End steps down with the down block of the OT, the Will LB ends up in a 1 on 1 foot race with the RB. This may be a bad match up. 

If the defense is fitting the run like a 4-4, the angles are much easier for the defense. The WS has a natural force leverage from width on the lead blocker. The Will LB can much more easily scrape over the top of the DE and pursue the RB. 

The 4-2-5 has the added advantage of disguise. On any play the LB's could bump during the cadence. Any of the three safeties could move into the role of the third linebacker. The defense can also show a 4-3 fit and bump back into a 4-4 run fit. The result is offenses being forced to constantly identify, communicate, and react to a defense changing it's run fits.

The versatility and flexibility are major contributing factors in the success and popularity of the 4-2-5. I'm going to continue the Basics of the 4-2-5 series this off-season as I have time. If there is anything you would like to see, drop a comment or send me an e-mail.


  1. Great article,
    You wrote about how it works against running play, but what about passing plays, how does it work?

    1. The coverage is a one high safety concept either cover 3 or cover 1.

  2. would you align in 4-3 look vs double tight full house. cover one or three behind it?

    1. Typically we are more 5-3 look vs. a 32 personnel formations as a starting point. SS on the LOS and the WS in the box as part of the "3 backer" run fit.

  3. 4-2 man free run fits versus one back runs would be greatly appreciated. I am curious as to whether it is generally better to box or spill to the side of the 3-technique. Also curious as to how to teach the reads of the LB who is stacked behind the 3-tech.

    Lastly, what happens when boxing and spilling versus the power read. If the end spills the power read, does he wrong arm the pulling guard, or is he able to recognize backfield action and tackle the QB.

    Any feedback would be greatly appreciated.