The route is called a "stutter comeback," and Richard Sherman admits defending it has been one of his few weaknesses. So Thursday night, when the Seahawks sat in a three-deep zone and Sherman read the play perfectly and intercepted his first of two Colin Kaepernick passes, he understood the significance.

The play depicted evolution, for Sherman and the entire Seahawks defense. For all the conversation this season about opponents figuring out the Seahawks, Seattle isn't some static defensive entity hoping to get by on deception. The Seahawks are a straightforward, hard-nosed football team that goes after offenses in a similar manner every game. In order to thrive that way, they must be smart and humble in recognizing how they can be beaten. Though they never really change, they must adjust. Somehow, they must be stubborn yet forward-thinking in their approach.

Their flexibility is now on display. It was evident as Sherman defended Brandon Lloyd and came away with an interception. And it has been evident for several weeks, as the Seahawks have changed the discussion from what's wrong to what's right about their defense.

Sherman explained his pick.

"So when I saw the first stutter, I knew that he was going to sit down," Sherman said of Lloyd. "I was waiting for his body language to tell me he was sitting down. I broke toward the receiver, eyes toward the receiver, and I looked up, and the ball was coming straight at me."

The Seahawks are returning to form because of such self-awareness, attention to detail, discipline and, most important, improved health. They have the best defense in the NFL again. Not just in reputation, or respect, or star talent. After perhaps the most impressive back-to-back defensive performances of the Pete Carroll era, the Seahawks lead the NFL in total defense, allowing a league-low 285.8 yards per game. Shockingly, they're giving up just 12.2 more yards per game than they did in 2013.

Two weeks ago, the Seahawks let Jamaal Charles and the Kansas City Chiefs run all over them. Now, they're four games from leading the league in total defense in back-to-back seasons.

In the last two games, both 19-3 victories, the Seahawks have limited Arizona and San Francisco to an average of 184 yards. The returns of middle linebacker Bobby Wagner and strong safety Kam Chancellor have helped the Seahawks get the best out of the defense they have now.

This time, they're doing it without an elite pass rush. They've been better in that area recently, but it's far from a strength. They've also forced more turnovers of late, but not at the ridiculous rate that they did a year ago. Instead of being purely a havoc-wreaking machine, the Seahawks are lining up and stopping opponents in a variety of ways.

At times, their run defense has carried them. With the Legion of Boom healthy again, the pass defense is getting back to its standard. And for everything opponents had been successful at doing - from relying on short passes and missed tackles to confusing the Seahawks with sophisticated route combinations and throwing the ball deep - the Seahawks have made the necessary corrections.

"Suffocating football," safety Earl Thomas said of the defense. "Everybody is tied in to what the formation is. People are studying. We're tied on a string. We're communicating, and that breeds confidence. We're really absorbed in each other out there, and it's nothing but love. It feels good."

Said linebacker K.J. Wright: "This defense is looking really good. We are on the rise. We are not looking backward now."

As impressive as the Seahawks were in 2013, their defensive recovery this season is a better story. A year ago, the defense was so loaded that Cliff Avril and Michael Bennett, the team leaders in sacks, weren't starters. The Seahawks had five starting-caliber cornerbacks. In the preseason, they cut players who went on to be starters for other teams.

This season, they don't have amazing depth. They've struggled to get sacks, to play good defense inside the 20-yard line and to get off the field on third down. They still commit too many penalties. Nevertheless, they lead the league in total defense and rank fourth in points per game allowed (18.4). And in the last two games, they kept Arizona and San Francisco out of the end zone.

"We had zero big plays," San Francisco tackle Joe Staley lamented when asked about his offense's performance against the Seahawks. "Zero."

Suffocating football, for sure.

"It took us some time to figure it out, but we have, and it's only as good as the next game out," Seahawks coach Pete Carroll said. "There's no question in the last two weeks that we have elevated our game."

Credit health for that. Credit their season-changing team meeting before the Arizona game. And credit the Seahawks' versatility in being able to find a slightly different way to excel.

The hard-hitting, fun-loving Seahawks defense is back - and evolving.

"Most definitely, we are having fun," Avril said. "We trust each other. I know that I trust the guys on the back end that they have my back, and they trust that we are going to get pressure on the quarterback. It is working for us, and we just have to keep it going."