The Seattle Seahawks have veered out of character and made two splashy free agent signings early in the league year. They didn’t step completely out of character, though, because they signed Cliff Avril and Michael Bennett to arguably the best free agent contracts of the offseason. Both defensive linemen were at the top of many free agent lists entering the free agent period, and the Seahawks locked them up for a combined $18 million over the next two years. So how will these signings impact the Seahawks’ defensive front in the 2013 season?

To understand how Seattle will use Avril and Bennett, we have to know how they scheme their front seven. Pete Carroll has been heavily influenced by Monte Kiffin, so at its heart, the Seahawks’ scheme is a 4-3 under, where the strength of the defensive line is shifted over the weak side of the offense (the side opposite the tight end, typically the offensive left), and the strong-side linebacker (Sam) is shifted down to the line of scrimmage. The 4-3 under is designed to control gaps, stop the run, and rush the passer. Typically, each of the front seven is responsible for controlling a single gap.

However, Carroll has revived a variant of the 4-3 under scheme that he learned under the legendary George Seifert of the late ‘80’s and early ‘90’s San Francisco 49ers. It’s referred to as the “elephant” or “Leo” scheme, and it’s almost a hybrid of a 4-3 and a 3-4 alignment.

Rather than using four big defensive linemen with their hand in the ground and three smaller linebackers in two-point stances, the Leo scheme uses a special hybrid player called, surprisingly, a Leo. The Leo is usually a little bit bigger than a 3-4 outside linebacker, but smaller than a 4-3 defensive end, and he must be a tremendous pass-rusher. He aligns on the weak side of the formation, slightly wider than a 4-3 end, and is responsible for controlling the C gap outside of the offensive tackle. On most plays, he’ll just pin his ears back and rush the passer. In Seattle’s scheme, that player has been Chris Clemons, and Bruce Irvin was drafted in the first round as Clemons’ heir apparent.

Because the Leo is typically weak in run support, the scheme calls for the strong-side defensive end (5-tech) to be an exceptional run defender. In Seattle’s scheme, that player is 6’4”, 325 pound Red Bryant. While the rest of the front seven each control a single gap, the 5-tech is responsible for two gaps. He’s not expected to create a lot of pressure on the quarterback, but he should be a black hole against the run and demand a double-team on a regular basis, which frees up the defensive tackles.

The two defensive tackles are a little more traditional. The nose tackle, or 1-technique, lines up over the shoulder of the center, and should be a stout run-plugger who can collapse the pocket. Brandon Mebane is a prototype 1-technique for the system. The 3-technique plays next to the 1-tech, lining up over the outside shoulder of the guard. He must be the premier pass-rushing defensive tackle on the team, as his job is to shoot his gap and collapse the pocket. When the interior of the pocket starts collapsing, the quarterback can’t step up to evade edge pressure, and the speedy Leo should have a good shot at him.

The Seahawks have been searching for their 3-technique for a while now. They signed Alan Branch two years ago after he busted as a nose tackle in Arizona. He’s nearly the same size as Bryant (6’6” and 330), but Seattle used him as a 3-technique, opting for better run defense at the expense of more explosive pass rush. Last offseason, they signed Jason Jones to alternate with Branch. The two complemented each other well, as Jones provides better interior pass rush while sacrificing a bit of run-stopping ability. Last year’s seventh round yielded Greg Scruggs who profiles as a more violent version of Jones, and Clinton McDonald was tendered a contract as a restricted free agent, so he’ll be back as depth at 1-tech and 3-tech. Finally, Jaye Howard was drafted in the fourth round last year, and he projects to 3-tech really well. However, he hardly cracked the active roster last year, so it’ll be interesting to see if he blossoms under the Seahawks’ new defensive coordinator (who was his college defensive coordinator), Dan Quinn.

So after laying all of that groundwork, how will the Seahawks’ front seven work out this season? Bryant will definitely be back at 5-tech, and Mebane will continue to hold down the fort at 1-tech. Clemons would continue as the starting Leo, but he tore his ACL in the playoff game against the Washington Redskins. He will likely start the year on the PUP list, meaning he won’t be available until after week 6 at the very earliest. So Bruce Irvin entered the offseason as the presumed starter at Leo. While he struggled in any type of full-time Leo role early in the season, Clemons’ injury thrust him into that spot in the Seahawks’ final game (the playoff game against the Atlanta Falcons), and he actually did better than many have been willing to credit him. He wasn’t strong against the run, but the Leo isn’t supposed to be. He wasn’t able to generate real strong pressure on the quarterback, but most of that was due to the complete lack of interior pressure. He got some good push on a number of occasions and flashed strength beyond what one would expect from a 6’3”, 245-pound defensive end.

The question is, did he show enough to leave Seattle comfortable slotting him in there to start the year, despite the addition of Avril (who is himself tailor-made for the Leo role)? Based on some of Pete Carroll and John Schneider’s recent comments, the answer appears to be yes. They’ve suggested that Avril will get some snaps as a Leo and as a third-down rusher, but that he’ll also play Sam, allowing them to move K.J. Wright to weak-side linebacker (Will) and keep all of their best players on the field. With Bryant at 5-tech, Mebane at 1-tech, Irvin at Leo, and Avril at Sam, the only position in the front seven without a clear starter is 3-tech. Enter Michael Bennett.

At 6’4” and around 280 pounds, Bennett is a little bit big for a traditional 4-3 defensive end spot, but also a tad bit small for a 3-4 defensive end spot. He’s also a little bit longer and lighter than a traditional 4-3 defensive tackle. He can provide a better pass-rushing option at 5-tech than Bryant, though he won’t be nearly as lethal against the run. However, as one of the best run-defending 4-3 defensive ends, who also happens to have thirteen sacks and nineteen tackles for a loss in the last two years, he may fit Seattle’s hybrid system perfectly as a 3-tech. Seattle’s 3-techs are only rarely asked to control two gaps, so they can easily add someone cheap like Branch or Tony McDaniel (who was brought in for a visit recently) to play rotational snaps as a two-gapping DT. Bennett wouldn’t be a complete loss against the run, and he plays with the speed and leverage to be a terrific one-gapping, penetrating defensive tackle between Mebane and Irvin.

Of course, Seattle only signed Bennett for one year and Avril for two years. They’re both young and could easily re-sign for longer after a successful 2013. But Seattle won’t be banking on that. They’ll be planning for life without them. They’ll need to groom their own 3-tech, their own Henry Melton or Geno Atkins. Is Jaye Howard the answer? He didn’t seem to be in 2012, but perhaps Dan Quinn can bring it out of him. Perhaps the “3-tech of the future” is in the 2013 draft? Perhaps Greg Scruggs is him. After all, he’s supposedly added ten pounds in the offseason, pushing him to 6’3” and 295 pounds--nearly prototypical 3-tech measurements.

Altogether, though, Seattle has more talent on their defensive line than just about any team in the league. Once Clemons returns from his ACL injury, they will be able to run out the ultimate third-down Nascar package: Irvin and Avril on the outside with Clemons and Bennett inside. No team in the NFL could match that type of pass-rushing prowess, especially in Seattle with the Twelfth Man screaming behind them. They can also shut down the run with Bennett and Bryant as defensive ends and Mebane and Branch/McDaniel/other bulky defensive tackle inside. On paper, they have depth, youth, versatility, experience, and talent. Now we just have to wait for another six months to see how it all pans out on the field.