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How USC's Switch to One-Gap System is Affecting the D-Line

"One-gap" versus "two-gap." You've heard the terminology, but what does it really mean? How is it affecting the USC defensive linemen this spring and in particular, star-in-the-making Rasheem Green.

If you weren’t an offensive or defensive lineman, you might have seen the terms “one-gap” and “two-gap” floating aimlessly through the vast catacombs of the interwebs without a true idea of what these seemingly simple football terms mean. Someone might have said them and they gondola’d through one ear canal and out the other like a whimsical Dr. Seuss rhyme.

But what are you going to see differently with Clancy Pendergast’s preference of a one-gap system rather than Justin Wilcox’s reliance on a two-gap system? How does it translate to the current Trojans on the field?

Wilcox and Steve Sarkisian wanted big-bodied defensive tackles and ends. Guys like Delvon Simmons and Claude Pelon with big frames and long arms that forced teams to use two blockers to keep them at bay were paramount. If a guard and and a tackle had to block Simmons on a running play, that meant Su’a Cravens or Cameron Smith should have an open lane to attack a running back carrying the rock. Two-gap systems are designed to free up playmaking linebackers to attack downhill and cause havoc at and behind the line of scrimmage.

With the graduation of five senior defensive linemen — four of which were around or above 300 pounds, the Trojans don’t necessarily have the manpower and body types to make that system most effective. Instead, Pendergast is more focused on a defense that attacks and strikes first rather than waiting to see the offense’s play type. Rather than lining up straight across from an offensive guard and either attacking on his inside or outside depending on what play the opposition runs, the defensive lineman positions himself between the offensive linemen and attacks the space between them, forcing the offensive linemen to have to quickly stop the defender from going straight through the line and into the backfield.

If that doesn’t clear it up a little better for you, here’s Kenechi Udeze’s explanation:

“When you are ‘head-up alignment,’ ‘two-gap,’ whatever you want to call it, you are literally asked to read. We’re attacking. That means we are striking people. We’re knocking them back and we’re getting off blocks. The other way around, in the 3-4 system, you have these big, huskier guys that literally just take up space and the linebackers do most of the tackling.”

Udeze said for defensive linemen to adjust, “it’s more or less training yourself in a different way.” He expects that as his young group of linemen get more experience, it will be able to do both.

“It’s different only because they’re freshmen, they’re sophomores. They haven’t really been acclimated to more than one system. Some guys have already shown that they can do it, it’s more or less them doing it on a more consistent level.”

The attacking scheme of the one-gap system has really helped a couple of defensive linemen shine. Guys like Malik Dorton that may not have been quite big enough to be the gap globber have been able to use their quickness and burst to knife through the offensive line to get in the backfield and cause trouble.

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Maybe it’s because we’ve seen the flashes of dominance — the essences of past Trojan greats —that we expected Rasheem Green to jump in and help immediately fill the void on the defensive line this spring. But while the five-star sophomore has made a number of plays, he hasn’t been that constant disruptive force that we know he has the ability to be. 

While Dorton, Christian Rector and others have enjoyed the switch to the one-gap system, Green felt more comfortable in the read-and-react style two-gap system that Wilcox implemented with bigger-bodied linemen that could occupy multiple blockers.

“It’s pretty different. I’m used to playing two-gap where you’re not on the shade of the guy, but straight up,” Green said referencing his pre-snap alignment in relation to the offensive lineman across from him. “I have to focus on playing half the man instead of the whole guy, which kind of hurts me in this new defense that we’re playing.”

Green was a little stubborn to take to the new system early on in the spring. He wanted to rely on his talent rather than hone his technique. But defensive line coach Kenechi Udeze continues to push Green and the 6-foot-5, 285 pounder with All-American potential has been starting to catch on more and more.

“Rasheem is one of those guys with a very, very high skill set, very high skill set, but he’s another guy that needs to hone in on his technique and his skill set and really work on just that,” Udeze said. “Long levers, 280 pounds…he’s what you want every defensive lineman to look like. But we’re not talking about talent, we’re talking about being technically sound.

“Rasheem has had a solid spring camp. I think the thing for Rasheem is he has to understand how to be submissive when learning and coached because it’s different for some guys. Some guys get it just like that while some guys it takes repetition to get out of an old groove that they used to be very-very centric to. 

When asked about some of the young studs on the defensive line, Clay Helton noted Green and his special skills, but added that he was proud of Green:

“He’s probably the one that I’m most proud of about taking some coaching from Practice No. 1 to now. He’s becoming a little bit more of a technician.”

Green said he’s become more comfortable in the new one-gap system because Udeze has put the defensive linemen through some new drills that focus in on attacking against one shoulder of an offensive lineman rather than going head to head with the hog mollies.

“We do a whole bunch of cool drills where we only practice half the guy, arm-over release and all that stuff, which is really essential to this defense,” Green said. 

And the effects of the new system for Green?

“There’s a lot less double teams since we’re not rushing three guys…and playing half the guy is a lot easier in passing situations since you only have to work half the guy to win.”


Follow Shotgun on Twitter: @ShotgunSpr.

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