Linebackers have passed through one after the other on their way to the NFL. The secondary has been made over several times. There have been three coordinators in the past three years alone.

Through it all, the University of Wisconsin football team's defense has remained one of the nation's best.

Connect the dots and you'll find the one constant in UW's spectacular run of defensive success has been the corps of down linemen, a sturdy, more-athletic-than-you-think group of team players who have anchored the defense for what seems like forever.

Senior ends Conor Sheehy, Chikwe Obasih and Alec James have been fixtures in the line rotation for four years, combining for 84 starts. Throw in a three-year regular, junior nose tackle Olive Sagapolu, along with promising young talents Garrett Rand and Isaiahh Lowdermilk and you have the most unheralded great defensive line in college football.

While the lines from Michigan, Ohio State, Alabama and Clemson get all the hype, UW's group is just as effective despite doing its job largely in the shadows.

"I feel like that's how it always goes around here," inside linebacker T.J. Edwards said. "But I think they're one of the best lines in the country."

The Badgers linemen might not have flashy statistics, though James' 5.5 sacks as an interior pass rusher should catch someone's eye, but they are the starting point of what has become one of the nation's elite defenses. Beginning in 2013, when Dave Aranda was hired as coordinator and flipped UW to a 3-4 scheme, UW's defense has rivaled Alabama's as the most consistently stingy unit in the country, only with a lot less fanfare.

Obasih and James sat out the 2013 season as redshirts, but during the past five years the Badgers have never been ranked worse than seventh nationally in fewest yards allowed per game and only once (2014) have they ranked worse than sixth in fewest points allowed per game. This season, UW is second in both categories, behind only top-ranked Alabama. The defense also is first in fewest rushing yards allowed, second in pass-defense efficiency and sixth in sacks per game.

Great defenses start up front and Sheehy, Obasih and James have set the tone on UW's defense for four of those five years.

"No question they've been a huge part of it," coach Paul Chryst said. "In so many ways, your offensive line and your defensive line are those foundational pieces. ... Just seeing their growth and their development and the unselfishness and the way they play and how hard they play, that rubs off on everyone on the defense and quite honestly I think it rubs off on our offense. You're talking about guys who are great examples, great leaders, care about this team, care about this program. It's been fun to see their development and their growth in it."

Since 2015, the line has been coached by Inoke Breckterfield, who followed Chryst to UW from Pitt, where he coached Aaron Donald, widely considered the best interior lineman in the NFL. Although the coordinators have changed — first Aranda, then Justin Wilcox, now Jim Leonhard — in each of the past three seasons, very little has changed up front. Well, except for the production. It has risen steadily.

The linemen on the 3-4 front are still asked to take on blockers, sometimes two at a time, and keep the lanes clear so the linebackers and safeties can run to the ball. Because of that, their individual statistics are often modest. The team's win totals are anything but modest, however. The fifth-ranked Badgers are 11-0 this season and 43-9 over the past four.

No one understands that correlation between the linemen doing their jobs and the success of the defense more than the players who line up behind them.

"They are probably the least-selfish guys on the entire team and they have been for many years," outside linebacker Garret Dooley said. "A lot of the time they're eating up blocks for outside linebackers, inside linebackers and safeties to make plays. They do it without asking questions. They'll take up two guys for you so you're free to go make a sack, go make a tackle for loss. And then whenever they do have their opportunities to win one-on-one stuff or get a big stop in the backfield and get a sack, they take advantage of it. ... I just think those guys are extremely special to this team because of what they do up front."

The line could get a late-season push from Obasih, who played in the opener, missed the next six games due to injury and has been rounding into playing shape since then. Regardless, the senior-dominated line will show up ready to play.

"I think the world of that group," Edwards said. "It's definitely the closest group we have on the team with a bunch of different goofy personalities. It's just a group who goes to work every day. They know what they have to do and they get it done. I think this year they've worked so hard on their pass rush that they've been able to beat all their mismatches and get after the quarterback. ... Us linebackers, we appreciate them like crazy because without them we couldn't do what we do. It's a special group of guys."

More than quarterback sacks and All-Big Ten Conference honors, that will be their legacy at UW.

Contact Tom Oates at toates@madison.com.

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