STATE COLLEGE, Pa. -- The past few years have brought historic changes at Penn State, from the men occupying the head coach's office to the names occupying the backs of the Nittany Lions' jerseys.

Yet until recently, Penn State's defensive line meeting room resisted renovation. It was one of few elements of the program that, in 2013, looked much like it did in 2005. Larry Johnson coached the group, as he had every season since 2000 (and, in some form, since 1996). And while the Lions' defense struggled for much of last season, the line still produced a first-team All-Big Ten performer, tackle DaQuan Jones, just as it did the previous five years.

But even the PSU defensive line couldn't evade the winds of change forever. After being passed over for Penn State's head-coaching job for the second time, Johnson in January declined a chance to remain with James Franklin's staff. Days later, he latched on at rival Ohio State.

Lions defensive linemen now take direction from a man known as Coach Chaos. You'll be able to hear Sean Spencer's voice from Row 80 of Beaver Stadium -- on game days. Spencer wants his Lions to be wild dogs, explaining, "The wild dog is the most efficient animal in the jungle in terms of hunting in a pack."

The 43-year-old dynamo with the "spastic" personality differs from that of his reserved, buttoned-down Penn State predecessor. But when it comes to standards, Spencer and Johnson are aligned.

"Traditionally, the D-line here has always been one of the elite in the country," Spencer told ESPN.com. "I know no other way but to have them rise to the expectations that I set forth and that they set forth for themselves. There's no excuse.

"I don't care who I've got out there. I expect to be dominant."

Spencer's message resonates with a group that, unlike others on a reduced roster, doesn't face dire depth challenges. The Lions return both starters at end -- Deion Barnes and C.J. Olaniyan -- and veteran reserve Brad Bars, who missed all of last season with a ruptured Achilles' tendon.

Sophomore Austin Johnson moves into the lead tackle position and Anthony Zettel, a converted defensive end, has been a good fit at the 3-technique tackle spot.

"The D-line is probably our strength," Franklin said. "We have the most depth at that position. We've got about four deep at defensive end and probably two-and-a-half deep at D-tackle."

If the depth holds up, it will help Penn State use a larger rotation that Johnson typically used. Defensive coordinator Bob Shoop said the Vanderbilt linemen he and Spencer coached last fall didn't average more than 40 snaps a game.

The coaches want to use five or six defensive ends, as Bars, junior Carl Nassib and redshirt freshman Garrett Sickels also are in the mix. A healthy rotation suits Spencer's wild dogs philosophy.

At Vanderbilt, he commissioned a painting of a Commodores football player blended with a dog, which he displayed in his office at Penn State this spring. He also took a giant dog bone to the field.

"Part of their survival is when they chase their prey down, for three to five miles they take turns biting at him," Spencer said. "One goes to the front, and when he gets tired, the next one comes. It's a really unique strategy in terms of the way they attack things. We rotate a lot of guys, so we just take turns nipping at quarterbacks and making plays in the backfield."

Vanderbilt recorded 28 sacks last season, which tied for fourth in the SEC. Spencer estimates 24 came solely from line pressure. He expects the same production at Penn State.

Defensive tackle has been Penn State's strongest position in recent seasons with players such as Jones, Devon Still, Jordan Hill and Jared Odrick. Although Zettel and Johnson aren't known outside Happy Valley, the coaches think that soon will change.

"Zettel has been been very, very disruptive this spring," Shoop said. "Austin Johnson falls in line of the beast D-tackles Penn State's had in the past. He's over 300 pounds, moves well, he's tough to move at the point of attack, got a big butt and legs."

Olaniyan led Penn State with five sacks last season, his first as a starter. Penn State looks for more from Barnes, the former Big Ten Freshman of the Year whose sacks and tackles for loss totals dropped by more than 50 percent from 2012 to 2013.

"What we're looking at is, how can we get him back to that?" Spencer said.

Spencer is pleased with Barnes' football knowledge and said all the linemen are asking "200- and 300-level questions" in meetings. Life without Johnson undoubtedly caused an adjustment -- "It's always tough to see somebody you call a family member leave," Olaniyan said -- but players quickly connected with Spencer, who lists relationship-building among his strengths.

"I grew up without a dad," said Spencer, whose father played for Michigan State in the 1960s. "Unfortunately, we don't have a relationship right now, and he's still alive. It's one of the things I'm least proud of, but at the same time, it made me who I am today. It made me have the ability to reach out to kids that probably are similar to me. I'm a little younger than Larry so they're not going to look at me as a dad, so to speak. They look at me as a big brother or an uncle.

"I think we've got some similarities in the way we care about our players, but I'm probably a little bit wilder than he is."

A little wilder and a little louder, but just as demanding.

"They both have the same philosophy as far as they want you to do everything perfect," Olaniyan said. "It's easy to embrace the new coaches when they have the same goal. We take pride as the Penn State D-line.

"Each game, we want everybody to see us as one of the best defensive lines out there. We want to be great."

At Penn State, some things never change.