Cornerback Richard Sherman and the other members of the Seahawks’ defense will be back in the spotlight at the 2014 NFL season begins Thursday night in Seattle (Photo by Al Bello/Getty Images)

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?

That is, of course, the question that is asked of all Super Bowl champions, and usually the answer ends up being no. 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 did so 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 perhaps even more intriguing because, in this era in which quarterbacks churn out 5,000-yard passing seasons relatively routinely, the driving force behind Seattle’s championship was a defense that dominated Peyton Manning’s record-setting Denver Broncos offense in the Super Bowl.

The unit had its headliners, including in-everyone’s-face cornerback Richard Sherman and do-everything safeties Kam Chancellor and Earl Thomas, but also one that relied on having 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.

The Seahawks’ depth on defense helped keep them fresh late into the season. (Brad Penner/USA TODAY Sports)

“The question, to me, is going to be the depth,” Moon said. “Last year they had a lot of depth, especially on the defensive line. 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. Injuries always come into play. If they stay relatively healthy, they have as good a chance as anyone.”

Among the offseason subtractions from the defense were linemen Red Bryant, Chris Clemons and Clinton McDonald (a trio which totaled 11 1/2 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 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 mindset 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’s obviously more to it than that. It’s about how you play. But from a preparation standpoint, it seems like they’re handling it well.”

There also is the matter of the NFL cracking down on clutching-and-grabbing tactics by defensive backs, making strict enforcement of defensive holding in the secondary and illegal contact by pass defenders beyond five yards from the line of scrimmage a major point of officiating emphasis for this season. Some observers have called that 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,” said Moon, a member of the Pro Football Hall of Fame. “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.”

The Seahawks led the league in total defense, scoring defense and pass defense during the 2013 regular season. But the offense also did its part. Seattle ranked fourth in the league in rushing offense and quarterback Russell Wilson threw 26 touchdown passes and only nine interceptions. He is the first quarterback ever to have a passer rating of at least 100 in each of his first two seasons.

Now he enters his third NFL season as a full-fledged star and eligible for a new contract next spring. Moon said he expects wide receivers Percy Harvin, back from last season’s hip troubles, and Jermaine Kearse to help Wilson add more big-yardage plays in the passing game to the Seattle offense. Wilson is yet to have even a 3,400-yard passing season.

“I think you’re going to see the same offensive style but it’ll be more explosive,” Moon said. “Kearse can make some big plays. Harvin is back and he can make some things happen. That’s an element you didn’t see as much last year. I don’t think you’ll necessarily see more [passing] attempts by Russell Wilson. But I think he’ll do more with them in terms of having some more explosive plays down the field.”