CINCINNATI -- Coach Marvin Lewis said in the offseason that there had to be a "changing of the guard" in some aspects of the Cincinnati Bengals' roster.

Nowhere is that more apparent than on the defensive line, where an influx of young talent has given the Bengals the ability to display several new looks this season.

"I love it," Bengals defensive coordinator Paul Guenther said. "Last year we had a lot of the same type of guys. And what I always like to do is diversify the kind of guys you have. ... That way allows you to say 'OK, I see a mismatch here; let's put him on that guy.'"

Officially, the only real change is the departure of veteran Domata Peko. Pat Sims, 31, will replace him as the starter on the depth chart. But Sims, who has been a backup rotational player for his career, won't be playing every down.

When Sims isn't in, he'll swap out with 22-year-old Andrew Billings. When the Bengals shift out of their 4-3 base, that's when the real fun begins.

The Bengals might turn to linebacker/defensive end Carl Lawson as an edge-rusher. Or they might sub in fellow rookie Jordan Willis, who led everyone in the preseason with four sacks. Ryan Glasgow might swap in at defensive tackle, and 25-year-old Chris Smith, obtained in a trade with the Jacksonville Jaguars, will find a role as well.

"We have a good rotation of guys. Carl is really a linebacker by trade, but he really brings some third-down rush for us," Guenther said. "Chris, Jordan. We've got three new guys that give us some speed and ability along with Carlos [Dunlap] and Mike [Johnson] and Geno [Atkins]."

Even veteran Michael Johnson might be finding himself in new situations. At 30, Johnson is the oldest three-down lineman in the group, and has never quite matched his peak form of 2012, when he had 11.5 sacks.

Perhaps looking to generate more rush after Johnson had only 3.5 sacks last season, the Bengals successfully experimented with moving him inside in nickel situations during the preseason.

"It's new life," Lewis told ESPN. "I can remember back to Pittsburgh, when we moved Greg Lloyd from outside rusher inside to the backer, and we put Chad Brown in his place and we got better. And sometimes just moving one guy and adding another guy. So we add Carl into the mix and we slide [Johnson] inside and now we've gotten better."

Added Guenther: "I just think the guards aren't used to his [6-foot-7] length. It's tough when you're trying to throw over the top of him in the middle of the field and he's got his hands in the throwing lanes."

There was something missing from the Bengals up front last season, and the results were a meager 33 sacks. They re-signed former Bengals defensive end Wallace Gilberry midseason in an attempt to find that spark.

Gilberry didn't make the team this year. What the Bengals were looking for in Gilberry, they might have found in Lawson and Willis -- players Lewis considers "mature beyond their years."

"People don't give intelligence up front enough credit," Lewis said. "You have to have smart guys up front too because they have to be able to work and fit together."

The abundance of youth is a departure from the Bengals' recent philosophy, which has celebrated reliability. In the last six seasons, they have rarely played rookies on defense, with the exception of 2014.

That's one of the reasons Johnson has earned the loyalty of the coaching staff. For better or worse, they know what they have in Johnson, who has remained one of the team's better run defenders.

"He plays the run defend very sound. We know what we're going to get all the time, and we're going to get it done the right way," Lewis said. "In base defense, in base run and everything ... he takes care of his job. He's 100 percent in that, and you've got to have that."

Things are changing in Cincinnati. After a 6-9-1 season, that reliable philosophy might just be thrown out the window in favor of youth.

"This was what I envisioned, and I feel good about that," Lewis said. "We wanted to put these guys in those situations all the time so that they would be ready to go. Now we've got to go prove it."