clock menu more-arrow no yes mobile

Filed under:

Oklahoma Sooners Football: Taking a look at changes to the run defense under Alex Grinch

Alex Grinch’s aggressive defensive scheme will leave OU susceptible to big plays on the ground.

NCAA Football: Oklahoma Spring Game Alonzo Adams-USA TODAY Sports

Alex Grinch developed a well-earned reputation in his three seasons with the Washington State Cougars for his defenses’ aggressive, fly-to-the-football mentality. Assuming the Oklahoma Sooners pick up on their new defensive coordinator’s vibe, it will represent a philosophical about-face from the bending-and-often-breaking approach of recent years.

That goes beyond just attitude. Grinch designs his defensive schemes to create havoc on the opposing side, which is bringing major changes to everything OU does on D.

Implementing Grinch’s preferred style will probably involve some ugly moments this fall. When it comes to stopping the run, the new scheme could set the Sooners up for some boom-or-bust performances.

When one-gap works...

The differences between the previous defensive regime and the new one start with the front.

We can quibble about whether the Sooners are shifting from a 3-4 scheme to a 4-2-5 or 3-3-5. Those distinctions don’t really tell us much about the responsibilities of the players lined up inside the run box – the imaginary rectangular area between the edges of the offensive line extending about seven yards into the defensive backfield.

What matters is that Grinch favors a one-gap approach in which defenders are taught to shoot through the lanes between blockers. As such, every defender has responsibility for an assigned gap, with the goal being to make plays on the ball in the backfield.

The clip above from WSU’s 2017 matchup versus the Stanford Cardinal offers a glimpse of what a single-gap scheme looks like when it works. The Cardinal are operating out of 12 personnel (one running back, two tight ends) with the quarterback under center, a rarity these days in college football. They set the strength of the formation to the field with both tight ends.

Although the initial pre-snap alignment isn’t shown here, the Cougars “stem” (i.e. shift) into a four-man over front. Defensive tackle Garrett McBroom (No. 99) comes out head up on the center, then moves before the snap to the 3-tech spot on the outside shoulder of the opposing guard on the strong side. The DT to the weak side (No. 50 Hercules Mata’afa) starts off as a 3-tech before shifting to the 1-tech between the center and the weak side guard. The defensive end on the strong side (No. 45 Logan Tatu) and RUSH linebacker on the weak side (No. 33 Dylan Hanser) line up on the outside shoulders of the tackles. The nickelback (No. 26 Hunter Dale) approaches the line of scrimmage outside the tight end, essentially giving WSU a five-man front.

In this case, every defender in the run box has an assigned gap:

  • DT 99 = B gap on strong side (between guard and tackle)
  • DT 50 = A gap on weak side (between center and guard)
  • DE 45 = C gap on strong side (between tackle and tight end)
  • RUSH 33 = C gap on weak side containing the edge (outside the tackle)
  • NB 26 = D gap on weak side containing the edge (outside the tight end)
  • MIKE LB (No. 37 Justus Rogers) = A gap on strong side
  • WILL LB (No. 13 Jahad Woods) = B gap on weak side

Stanford appears to be running a split zone concept with the wing TE coming across the formation to block the RUSH LB. I say “appears” because WSU’s front blows up the play so quickly that it barely has a chance to develop.

The strong side DT rockets through the B gap on the snap. He meets the running back almost as soon as he takes the handoff from the quarterback. The MIKE and RUSH LBs help clean up, and the play goes for a one-yard loss.


Compare what the Wazzu linemen are doing above with what OU is up to here:

This image from the Sooners’ 2017 win over the Ohio State Buckeyes pretty much sums up the difference between the one-gap scheme favored by Grinch and the two-gap front that Mike Stoops implemented in his second stint as OU’s defensive coordinator. When the DLs are playing two-gap, they’re aiming to strike blockers in front of them and read the flow of the play.

Note how OU sets its front prior to the snap:

Both defensive ends line up in a 4i-tech across from the inside eye of the offensive tackles. The nose tackle is playing a 0-tech head up on the center. That’s in stark contrast two Cougars’ DL alignment, where the DLs set up in the lanes between the OLs.

Instead of trying to shoot into the gaps between the blockers, OU’s linemen want to clog up the interior. That puts the LBs in position to make a stop.

One-gap gives and one-gap takes

Generally speaking, the two-gap approach seeks to “minimize the damage” of a run play. The calculus of a one-gap is different.

A one-gap scheme is awesome when you get penetration into the backfield. This is not so awesome:

In this clip above from a 2016 game against the Oregon State Beavers, Wazzu is again playing a four-man over front. However, once the ball is snapped, Mata’afa, who is playing 1-tech on the weak side of the formation, crashes across the center to fill the strong side A gap. The WILL LB (No. 31 Isaac Dotson) appears to have responsibility for filling the vacated A gap on the weak side.

Unfortunately for the Cougars, their call plays right into the hands of the Beavers. OSU’s center engages Mata’afa before passing him off to the strong side guard. The center then seals off the WILL, creating an enormous hole through what was the strong side A gap. Meanwhile, Robert Taylor (No. 2) is hustling from his spot at safety to contain the edge on the weak side, meaning no one is home in run support on the third level of the D.

The OSU running back goes virtually untouched as he dashes 90 yards to the end zone.

The moral of the story: Offenses can use the aggressiveness of a one-gap defense against it to set up big gains on the ground when gaps don’t get filled. Hopefully, the negative plays generated by OU’s run defense will more than offset the occasional home runs that it allows.