Break It Down, Divisional Round: Bruce Irvin vs. Atlanta's offensive line

Bruce Irvin has been a pleasant surprise as a pass rusher, but there are doubts about his ability as a complete end. (Kevin Casey/Getty Images)

"This is Bruce (Irvin)’s opportunity. It’s what we drafted him to play. We’ll see how he does. We expect him to really play well as he steps up."

Those are the words of Seattle head coach Pete Carroll from Monday, when he announced that standout defensive end Chris Clemons would miss the remainder of the playoffs with an ACL injury. The next man up is Irvin, a rookie out of West Virginia, who was a surprise pick at No. 15 overall during last April's draft.

You can dig a little deeper into what a Clemons-for-Irvin switch on the Seattle line might mean for Irvin here.

But what does that change-up do to the Seattle defense? And how might Atlanta be able to attack a Clemons-less front, in this weekend's NFC divisional round playoff game?

The latest "Break It Down" tackles those questions ...

Let's start with the basics: Here's a look at how the Seahawks lined up against the Redskins on the play that saw Clemons injure his knee. It was a 3rd-and-5 (a passing situation), so Clemons lined up on the right (red X), with Irvin (No. 51) at left end. Clinton McDonald (No. 69) and Greg Scruggs (No. 98) filled the inside spots.

The players filling those tackle roles varied -- Brandon Mebane and Alan Branch saw plenty of action in pass-rushing situation, too -- but that, generally, is how the Seahawks tried to pair Clemons and Irvin. The benefit was that Pete Carroll could pick his spots with his athletic rookie, allowing him to do what he does best, which is get upfield on passing plays (Irvin's the X on the right in the photo below).

Right after Clemons first went down Sunday, the Seahawks slid Irvin to his spot at right end. Immediately, the Redskins attacked that spot with a toss play that direction.

Washington had a lot of success attacking opposite Clemons' spot on the line early, using the toss to Alfred Morris. With Clemons sidelined, Washington tested the waters off the other edge.

Irvin has the X above. The Redskins started in their pistol look, with Darrell Young as a fullback and Morris behind Robert Griffin III. Tight end Logan Paulsen helped to seal the edge, where Morris headed.

As for Irvin ...

That's not so good.

Matched up against left tackle Trent Williams, Irvin wound up being driven almost to the sideline, as Morris slipped inside him for a solid six-yard gain.

This highlights the red flags for Irvin as an every-down player -- he has played only sparingly against the run this season and, while his sleek frame benefits him when he's pass rushing, it's a detraction on the ground.

Now, how much of a problem will that be against Atlanta? Probably not as big a one as it could be against, say, San Francisco -- a team that prides itself on having a power run game. That said, Atlanta will still try to establish both Michael Turner and Jacquizz Rodgers. The Falcons' talented offensive tackle duo of Tyson Clabo and Sam Baker might make life difficult for Irvin and the Seahawks' front, too.

After Irvin's initial difficulties on the right side of the defensive line, the Seahawks opted to move him back to his normal spot on the left -- here, on a 3rd-and-11, with Seattle using just a three-man line (Irvin, McDonald and Scruggs) and blitzing LB Bobby Wagner (No. 54).

Will Seattle continue to use Irvin off the left edge this coming Sunday? Carroll said only that Irvin will start at the "Leo" spot -- a position in Carroll's defense reserved for a fast rusher, almost like a 3-4 outside linebacker.

Irvin, as mentioned, has done a lot of his work from left end, but will the Seahawks try to play the matchups? Playing Irvin on the left means he'll deal with Clabo; on the right is Baker. Neither is a slouch, but Clabo, a 2010 Pro Bowler, may be the stiffer test of the two.

The Falcons have had more success running the football behind Clabo, as well. According to Pro Football Focus, Atlanta averaged 4.8 yards per carry on run plays behind or wider than the right tackle spot (Clabo's); that number was 3.3 on similar carries the other direction.

Clabo is more than capable of clearing space in the run game, as evidenced by the shot below, which shows Clabo clearing New Orleans' Cam Jordan as fullback Mike Cox eliminates Jonathan Vilma.

One of the benefits for the Seahawks of keeping Irvin at left end is that it puts him in better position to deal with rollouts or scrambles -- Matt Ryan, as a righty, would prefer to head that direction for a pass outside the pocket.

An Irvin sack of Griffin Sunday showed exactly why he's so lethal to the QB's throwing side.

Washington lined up in the I, then motioned receiver Josh Morgan in behind the line. Morgan kept coming and tried to chop Irvin, as Griffin faked a handoff and rolled to his right.

Irvin hopped over the Morgan block attempt, only to find Young waiting for him as a last line of RGIII protection. Irvin also managed to shed that block, then took down Griffin.

Granted, a more mobile Griffin might have taken off (this play was the one that preceded Griffin's knee injury), but Irvin still showed off his incredible talents ... and Matt Ryan is not necessarily a scrambling quarterback.

Here, for example, on a play against the Giants, Clabo wiped out Jason Pierre-Paul, giving Ryan a clear (and gaping) lane through which to scramble. Instead, Ryan slid a couple steps to his left, away from the Pierre-Paul rush, and fired downfield.

No matter which side Irvin lines up on (or what Seattle chooses to do on the other end), the Falcons will vary their protections to add a little extra help for Matt Ryan.

On the 3rd-and-9 below, Atlanta started with Ryan in the shotgun and Rodgers to his right. The Falcons then motioned Jason Snelling in to Ryan's left, giving the Atlanta QB a split-RB look in the backfield. Both Rodgers and Snelling then chipped the DE on their respective sides of the field, before releasing into pass patterns.

There is little question that Atlanta will try to test Irvin early, especially in the run game. If he cannot hold up there, the Falcons might use more or Turner and Rodgers until the Seahawks counter.

And in the passing game, Atlanta will have multiple options: rolling the pocket from Irvin, using a back to help block him, just letting Clabo or Baker go one-on-one. Because of that, not only does Irvin need to deliver a terrific performance Sunday, but so too does the rest of Seattle's line.

Remember, not only is Irvin taking Clemons' spot in the lineup, but some other Seahawks player (Red Bryant, Scruggs, etc.) has to then fill Irvin's pass-rushing shoes in long-yardage spots.