Cornerback Richard Sherman is a stalwart in the Seahawks defense. He and safety Earl Thomas signed contract extensions in the offseason. (Marcio Jose Sanchez/AP)

It is the age of offense in the NFL, and it is, more than ever, a quarterbacks’ league. But as the new season opens Thursday night in Seattle, the defending champion Seahawks will trot out the defense that propelled them to a dominating Super Bowl triumph seven months ago and begin to answer the question: Can it be done again?

It is the question asked of all Super Bowl champions, one that usually is answered in the negative. Only eight times has a team successfully defended its Super Bowl title, and no NFL franchise has won consecutive championships since the New England Patriots in the 2003 and 2004 seasons.

But the repeat bid of the Seahawks, who host the Green Bay Packers in the NFL’s season-opening game, is made most intriguing because of its ability to flourish in an era that emphasizes offense. In this time of relatively routine 5,000-yard passing totals, it was Seattle’s defense that fueled its 2013 success and dominated Peyton Manning’s record-setting Denver Broncos offense in the Super Bowl.

The Seahawks led the league in total defense, scoring defense and pass defense during the 2013 regular season. The unit had its headliners, including in-everyone’s-face cornerback Richard Sherman and do-everything safeties Kam Chancellor and Earl Thomas, but also relied on role players — interchangeable parts at a number of positions. The issue this season, according to former Seahawks quarterback Warren Moon, will be whether enough reliable players emerge to replace those who exited during the offseason.

“Last year they had a lot of depth, especially on the defensive line,” Moon said. “They shuffled guys in and out of the lineup, and the backup guys were almost as productive as the starters. Nobody had to play too much, and they were really fresh at the end of the year. You saw that in the playoffs and Super Bowl. We have to see if some young guys come through and they can have that again.”

The Washington Post's Gene Wang discusses which NFL players are moving up and down on the fantasy football draft board. (Kyle Barss/The Washington Post)

Among the offseason subtractions from the defense were linemen Red Bryant, Chris Clemons and Clinton McDonald (a trio that totaled 111 / 2 sacks last season) and cornerbacks Brandon Browner and Walter Thurmond. But the core of the defense has remained mostly intact, and the Seahawks signed Sherman and Thomas to contract extensions during the offseason.

“They’ve been smart about how they’ve put that thing together — how they structured the team, how they structured deals,” former San Francisco 49ers guard Randy Cross said. “They’ve been preparing for this for two years. Hats off to Pete [Carroll, entering his fifth season as the team’s head coach] for that. It’ll be interesting to see how it plays out.”

Cross won three Super Bowl titles during his playing career with the San Francisco 49ers but none of them back to back. He retired after the 49ers won the first of two straight Super Bowl championships in the 1988 and ’89 seasons. He said these Seahawks seem to have the proper mind-set to replicate their 2013 success.

“I’d say early on they’re looking focused,” Cross said. “Some guys took care of contract things, so there were some months of, ‘How come I’m not making more money?’ But it seems like they’re taking care of the repeat thing pretty well. They’re embracing it. They’re not ignoring it and making it the 800-pound gorilla in the room.”

There also is the matter of the NFL cracking down on clutching-and-grabbing tactics by defensive backs, emphasizing enforcement of defensive holding in the secondary and illegal contact by pass defenders beyond five yards from the line of scrimmage. That perhaps was a reaction to the Seahawks’ success, given the physical style for which Seattle’s celebrated secondary was known last season.

Browner, now with the Patriots, said during training camp that defensive backs with that style can’t overhaul how they play.

“You don’t want to be out there thinking about getting penalties,” Browner said. “You play your game and let the chips fall where they may.”

Browner’s former teammates might be taking a different approach, however. Even while penalty flags were flying at a dizzying rate league-wide during the NFL preseason, the Seahawks were called for only three illegal contact penalties and zero defensive holding infractions.

“I don’t think the secondary rule has hurt them very much, if you look at the preseason,” Moon said. “I think they’ve already adjusted to it. They do most of their stuff in the first five yards anyway. They’re strong and physical, and they can disrupt [receivers’] patterns in those first five yards. I don’t see it hurting them that much.”