Ohio State is hiring Oklahoma State’s Jim Knowles as its next defensive coordinator, tasking him with shoring up a unit that struggled at various points this fall.

In a statement released Tuesday night, coach Ryan Day said Knowles had accepted the position and would take over as the defensive coordinator on Jan. 2.

The Buckeyes will continue with their current staff of assistant coaches through the Rose Bowl on Jan. 1 before opening up a spot for Knowles to come aboard.

“What is most important at this time is that we put our players in the best position possible to finish this season with a win in the Rose Bowl,” Day said.

If Knowles is able to turn around the Buckeyes’ defense in the coming seasons, it won’t be his first rebuilding project.

He arrived at Oklahoma State in 2018 when the Cowboys had one of the worst defenses in the nation.

After ranking No. 112 in total defense in the Football Bowl Subdivision in his first season, incremental improvement followed.

They went up to No. 82 in 2019 and No. 44 in 2020 before their biggest breakthrough arrived.

Oklahoma State had one of the nation’s best defenses this fall, ranking No. 3 in total defense and No. 7 in scoring defense. The group allowed only 4.41 yards per play, an average that ranked No. 4. Only Georgia, Wisconsin and Cincinnati were more efficient on that side of the ball.

The performance elevated Oklahoma State, a program mostly known for high-scoring offenses throughout Mike Gundy's coaching tenure, into contention for a spot in the College Football Playoff deep into the season, rising as high as No. 5 in the second-to-last rankings.

A 21-16 loss to Baylor in the Big 12 championship game on Saturday dashed those playoff hopes, but through no glaring fault of Knowles’ group that shut out the Bears in the second half and held them to a season-low 242 yards of offense.

Knowles was recognized for his effort when he was named one of the five finalists for the Broyles Award, which recognizes the top assistant in college football. Michigan offensive coordinator Josh Gattis became the ultimate recipient earlier Tuesday.

Other Power Five conference programs were believed to have been in pursuit of Knowles before he and the Buckeyes reached an agreement. He’ll likely be up for a pay raise at Ohio State after reportedly making $800,000 per season with the Cowboys.

A Philadelphia native, Knowles has no ties to Ohio State and spent most of his coaching career on the East Coast until he was hired by Oklahoma State.

He previously spent eight seasons on David Cutcliffe’s staff at Duke, where he was the defensive coordinator and also coached linebackers and safeties. His time in Durham coincided with one of the best stretches for the program since World War II, including four straight bowl appearances between 2012 and 2015. The Blue Devils also had their first-ever 10-win season in 2013.

From 2004-09, Knowles led Cornell, his alma mater, where he was a defensive end in the 1980s. In six seasons as a head coach in the Ivy League, he went 26-34.

A hallmark of Knowles’ best defenses has been aggression. Oklahoma State was especially smothering this season and often disrupted offenses behind the line of scrimmage. The Cowboys’ 54 sacks and 113 tackles for loss were atop the FBS.

Knowles used multiple defensive formations, moving between a 4-3 and 3-3-5.

With limited depth at linebacker, the Buckeyes moved from a 4-3 to a 4-2-5 alignment this season, but have always used four down linemen.

Two days before announcing the pending hire of Knowles, Day avoided tipping his hand about potential staff changes, maintaining that his team’s focus was on preparation for their Rose Bowl matchup against Utah with practices beginning Friday. He and his staff have also been out on the road recruiting ahead of next week’s early signing period.

But movement on the staff has appeared likely since September when he stripped defensive coordinator Kerry Coombs of play-calling responsibilities and handed those over to secondary coach Matt Barnes in the aftermath of an upset loss to Oregon.

Coombs’ current contract runs through January after he signed a two-year deal in 2020 to run the Buckeyes’ defense and return to a program that he spent six seasons as a cornerbacks coach.

Some of the issues for the defense seemed to be fixed with Barnes calling plays, progress that put him in a position for a potential promotion.

After being gashed by the Ducks in their second game, the Buckeyes were filling gaps and stopping big plays. In a rout of Michigan State on Nov. 20, they bottled up Kenneth Walker III, the Big Ten's running back of the year and a Heisman Trophy candidate.

But the trend line didn’t continue, and they were steamrolled by Michigan in a 42-27 loss over the Thanksgiving weekend that eliminated them from reaching the playoff for a third consecutive season and winning the Big Ten for a fifth straight year.

The Wolverines ran for 297 yards, their most in The Game since 1995, and prompted Gattis to label the Buckeyes as a “finesse team, not a tough team" two days later.

Ohio State ultimately finished nationally No. 50 in total defense and No. 25 in scoring defense.

Knowles will be the third defensive coordinator hired by Day since he took over the program from Urban Meyer in 2019.

He first brought in Jeff Hafley, who put together one of the nation’s best units in his sole season, helping the Buckeyes recover from one of their worst defensive performances in program history in 2018.

The following seasons saw mixed results under Coombs.

Now it’s Knowles’ turn to get Ohio State back on track.

Joey Kaufman covers Ohio State football for The Columbus Dispatch. Contact him at jkaufman@dispatch.com or on Twitter @joeyrkaufman.

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This article originally appeared on The Columbus Dispatch: Ohio State football hires Jim Knowles as defensive coordinator