The All-22: Dominant defensive line play is the key to Carolina's resurgence

From front to back, Luke Kuechly (right) and Carolina's defense are a major problem for opponents. (Ben Margot/AP) One of the reasons the Carolina Panthers

From front to back, Luke Kuechly (right) and Carolina's defense are a major problem for opponents. (Ben Margot/AP)

One of the reasons the Carolina Panthers hired head coach Ron Rivera before the 2011 season is that the man knows how to turn a defense around. And the Panthers certainly needed that help -- in 2010, their defense ranked 16th in Football Outsiders' opponent-adjusted metrics, dropping to dead last in Rivera's first year. But over the 2012 and 2013 seasons, while all the focus was on Cam Newton's quarterback development and body language, Rivera and defensive coordinator Sean McDermott were building a fairly titanic front seven -- the kind that could compete with any in the NFL when the conversation came around to the league's best in that department. The 6-3 Panthers are buttressed by Luke Kuechly's legitimate Defensive Player of the Year candidacy, linebacker Thomas Davis is criminally underrated, and if you want to see an active and effective defensive line in everything from base fronts to advanced blitzes, this group is as good as it gets. Carolina currently ranks first in FO's metrics, and only the Kansas City Chiefs have allowed fewer yards and points this season.

Opponent-adjusted metrics are important when discussing the Panthers, because so many have discounted their success as the result of inferior competition. Rivera would like to think that his team put such thoughts to rest when it traveled to Candlestick Park and limited the San Francisco 49ers' offense to three field goals and 151 yards on 52 plays.

TROTTER: Panthers take place among the NFC elite with gritty win over 49ers

"You just have to put yourself in the position where we can force the other team to kick field goals and you get a chance to win," Rivera said after the game. "There were a lot of good things that went in that game. The defense played extremely well. I am very pleased with the effort we got from those guys. I thought a couple things that we did offensively, we gave ourselves a chance and put ourselves in a position a couple times to score and we took advantage of it. Again, this one really did come down to the way the defense played.”

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Rivera and McDermott dialed up some subtle and interesting wrinkles to counter San Francisco's power-based offense, the hallmark of the 49ers' five-game winning streak coming into the contest. Operating for the most part out of a four-man base front, the Panthers brought Davis down to the line to reinforce the edge defense against the run game -- not only running back Frank Gore, but the rushing threat of quarterback Colin Kaepernick. This strategy was reinforced by Kuechly's awareness and ability to cover as much ground as any linebacker in the game. And in short-yardage situations, Carolina really made it interesting.

The Panthers rotate their defensive linemen out fairly consistently -- four tackles and four ends took snaps against San Francisco -- and I really liked what they did when the 49ers had a third-and-2 from the Carolina 33-yard line with 11:28 left in the first quarter. The 49ers lined up in a traditional power set -- a tight end on either side of the formation in-line, and fullback Bruce Miller lined up just ahead of Kaepernick in an offset Pistol look. Carolina countered by positioning five defensive linemen out front -- Frank Alexander (90), Dwan Edwards (92), Kawann Short (99), Charles Johnson (95), and Greg Hardy (76). They were essentially using Hardy as an extra end in an unbalanced defensive front -- a fascinating twist on what offensive lines frequently do with offensive tackles -- and it paid off with a drive-killing stop.

The 49ers went with slide protection to their left, and sent Miller and right tackle Anthony Davis to the second level to close Kuechly off. That left Johnson unblocked, and Hardy with only tight end Vance McDonald to deal with. No contest. Gore was taken down for a loss of one yard,  and San Francisco had to settle for a field goal.

The Panthers are also exceptional when it comes to creating interior pressure in base fronts. With 2:23 left in the first quarter, Edwards just demolished right guard Alex Boone on a sack of Kaepernick, but he had a lot of help. The 49ers had first-and-10 at their own 24-yard line, and tight end Vernon Davis motioned from left to right to help left tackle Joe Staley block Hardy. Left guard Mike Iupati and center Jonathan Goodwin double-teamed Short at the one-tech position, leaving Davis on Johnson and Boone one-on-one on Edwards. It was a mismatch from the start.

Davis (58), Kuechly (59), linebacker A.J. Klein (56) and safety Quintin Mikell (27) motioned to the strong side when Davis moved over, and Mikell covered Miller's short route. With Miller out of the picture as a blocker, Gore was left to help Boone with Edwards after Edwards rolled around Boone with impressive speed and power. At the same time, Hardy flew around the blocks of Davis and Staley, leaving Kaepernick with no room to bail out of the pocket.

Right before the sack, you can see Gore's decision point -- he's set to block Edwards, but he's watching Hardy close in from the backside.

As a result, Edwards was unobstructed in his path to Kaepernick.

The Panthers next face the New England Patriots on Monday Night Football, and Pats head coach Bill Belichick is not among those who believe that Carolina's defense is a paper tiger.

"They’re very disruptive up front," Belichick said on Monday. "I think it starts with that. Johnson is an outstanding player. They have two good ends with Hardy and Johnson. Their inside guys have played well. They’ve got Edwards and getting him back into the mix. Their linebackers are pretty active: Davis and Kuechly are very good pass defenders. I would say that overall they’re a pretty instinctive team ...  you see those guys making a lot of plays. I’d put Kuechly in that category too -- Davis -- those guys make a lot of plays just because they kind of sense it. They sniff it out and get a step or a step and a half ahead on the play because they anticipate and then they’re there to make it.

"They don’t do a million different things but what they do, they do well. They don’t have a lot of bad plays. You really have to earn everything. You have to block them. You have to get open, you have to be able to operate pretty quickly because they close in on you in a hurry on the front. They do a good job of being sound, taking care of everything, playing physical and then if you’re sloppy, then they’ll make you pay for it. You have to do a good job avoiding negative plays, staying out of long-yardage --  getting into a bunch of third-and-10s and second-and-15s and stuff like that, or it will be a long day."