Baltimore defenders Paul Kruger (99) and Chris Carr (25) converge on St. Louis running back Steven Jackson (39). The Ravens lead the NFL in scoring defense. (Jeff Curry/GETTY IMAGES)

With pass-happy NFL offenses threatening to rewrite significant portions of the record book this season, defenses are scrambling to find ways to keep pace. Collectively, offenses league-wide have established all-time bests through the season’s first three weeks, with 2,157 points, 153 passing touchdowns and 23,560 net passing yards.

Given the modifications to the rules in the past decade and the possible lingering effects of an offseason without practices, the question has become: Is it even possible to play dominant defense in the NFL any longer? Or even very good defense?

“I do think it’s still possible,” former Tampa Bay Buccaneers safety John Lynch said. “But certainly it’s a lot tougher.”

Said Matt Millen, the veteran broadcaster and former NFL executive who won four Super Bowls during his playing days as a linebacker: “It’s relative. What’s dominant defense in today’s NFL? It’s not what it was in 1960, in 1970, in 1980, in 1990. You have to rush the passer and you have to cover. You need edge pass rushers and you need cornerbacks.”

The transformation of the NFL began when the league’s rule-making competition committee made it a point of emphasis for officials prior to the 2004 season to eliminate clutching-and-grabbing tactics by defensive backs on wide receivers more than five yards down the field. More recent safety-related rule changes have restricted hits on quarterbacks and wide receivers. The result has been the most passing-friendly era in the sport’s history.

“You look at the 2000 Ravens and the ’85 Bears, people consider those the two best teams ever, defense-wise,” Ravens cornerback Chris Carr said. “But you could touch receivers after five yards then. You can’t do that now. Defense would be a lot different if we could jam receivers all the way down the field.”

Some players have been critical of the league’s approach to restricting hits to the head of an opponent. But Carr’s teammate, Ravens linebacker Jarret Johnson, said the restrictions were necessary.

“They had to do something,” Johnson said. “People were getting knocked out. There were a lot of high shots. . . . It’s something they had to do. You just have to adjust the way you play.”

But Lynch said there has been a competitive effect.

“When I think of the great defenses in recent memory — the ’85 Bears, the Ravens in the 2000 era, ours in Tampa — you struck fear in people,” said Lynch, who also played for the Denver Broncos and now is an NFL analyst for Fox. “Today with all the rules, you don’t see it any more.”

Defensive backs are coached differently, Carr said.

“Your [defensive backs] coach used to say, ‘Hey, if they come across the middle, make them pay,’ ” Carr said. “Now they say, ‘If they come across the middle, pick the ball off or take a good tackle angle.’ ”

Defense in age of offense

So how must teams go about playing defense in the age of offense? Millen said it’s all about pass rushing and coverage in the secondary.

“Great defense now is: Can we get consistent pressure? And can we cover?” Millen said. “No one even talks about the running game. We have gone back to the future. We have become the AFL of 1964, ’65, ’66.”

The key, Millen said, is to have multiple productive pass rushers, as with the unbeaten Detroit Lions. He said that Green Bay Packers linebacker Clay Matthews, who had 131 / 2 sacks last season but has managed only one in three games this season, is being double-teamed more often on blocks after defensive tackle Cullen Jenkins departed for the Philadelphia Eagles via free agency following the NFL lockout.

Others said defenses must continue to stress stopping the running game, even in this time of prolific passing.

“It’s still the same things as ever to me,” Lynch said. “You have to have some impact, special players. I still believe you have to stop the run and make the offense one-dimensional. Clearly, you have to get after the quarterback. You have to knock him down. And you have to be a great tackling team. It is really sloppy now. All these catches aren’t being made 60 yards downfield. There are a lot of receivers catching short passes, breaking tackles and going a long way.”

Millen, too, said that tackling fundamentals by many NFL defenders are extremely poor and might be worsening because of new restrictions in the sport’s new labor agreement limiting contact in practices.

“When you’re hardly ever in pads,” Millen said, “you’re seeing the difference in the NFL right now. . . . It shows up in poor fundamentals in tackling and offensive line play.”

Former Washington Redskins and Houston Texans general manager Charley Casserly said he thinks the season must play out further before firm conclusions should be drawn. But for now, he said, defenses appear to have suffered more than offenses from the lack of formal practices during the 41 / 2-month lockout.

“Everyone thought that defenses would be ahead of offenses without the offseason preparation because of the blitzes and pass-protection issues,” Casserly said. “But it seems to me what we’re seeing is that defenses are behind offenses. I don’t know that you had enough time in the offseason to work on it and be ready to defend all the complex things that you’re seeing with these passing offenses.”

The Ravens’ way

In Owings Mill, Md., the Baltimore Ravens’ training facility is one of the few where defensive players can still walk around proudly.

“I think the standard here is a little different with the Ravens, how we’ve been successful on defense throughout the years,” Carr said here late in the week. “We’ve been good thus far. Hopefully we keep it up. A team like us, we have the players. We have the mentality. We have the system and we’ve all been in it. We have that advantage there. Our mentality hasn’t changed.”

Carr said he has seen defensive confusion and missed coverage assignments around the league this season. That has not been a major issue for the Ravens, who are surrendering 13.3 points per game and lead the league in scoring defense.

“It all comes back to number one stopping the run, making a team one-dimensional, and then playing good, sound coverage and getting after the quarterback,” Johnson said. “It’s always the same. . . . You can still do it. It’s obviously not impossible. It is tough with the rules with quarterbacks and stuff. But you’re still capable of playing dominant defense.”

Hall of Fame linebacker Sam Huff, a longtime analyst on radio broadcasts of Redskins games, said the league should guard against tipping the competitive scales too far toward offenses.

“I always thought we were paid to hit people,” Huff said. “The NFL is a game of contact. It’s a great game. . . . But I’m concerned about the future of the sport if things keep going the way they’re going. If you make it touch football, no one will pay $100 to go see it.”

But Casserly, a former member of the competition committee, said no safety-related rule changes will be reversed and he sees no obvious modifications to be made to aid defenses.

Lynch said “maybe at some point people will say these rules have gone too far and we need to do something to help the defenses,” but added: “I don’t count on it. I know the NFL likes all these points.”

So defensive players will have to learn to cope with “the new normal,” as Millen called it.

“And of that new normal,” Millen said, “there will be a best running game, a best defense. We’ll say, ‘They played great defense,’ and the score was 42-41. We’ll say someone led the league in scoring defense and they gave up 39 points a game.”