Back by overwhelming demand, FootballScoop will once again examine the assistant coaching hires that will have the biggest impact on the college football season and the coaching job market in the 2019 season and beyond.

No. 19: Bryan Brown, Louisville

No. 18: Phil Longo, North Carolina

No. 17: Les Koenning, Kansas

No. 16: Andy Avalos, Oregon

No. 15: Joe Cauthen, Houston

No. 14: Bodie Reeder, North Texas

No. 13: Mike MacIntyre, Ole Miss

No. 12: Andy Ludwig, Utah

No. 11: Kenny Dillingham, Auburn

No. 10: Jim Chaney, Tennessee

No. 9: Sean Gleeson, Oklahoma State

No. 8: Dan Enos, Miami

No. 7: Kendal Briles, Florida State

Who: Greg Mattison Jeff Hafley, Ohio State

Titles: Co-defensive coordinators/secondary coach (Hafley)

Previous stops: Michigan defensive coordinator (2011-14), defensive line coach (2015-18)/San Francisco 49ers defensive backs coach (2016-18)

Why they’re important: We all knew Ryan Day would remake the staff upon ascending to the head coaching role — but nobody knew he would do it like this. In conjunction with Greg Schiano’s expected departure, Day put the defense in the hands of an odd couple two-some of the weathered Greg Mattison and Jeff Hafley.

Mattison has been coaching nearly 50 years, almost entirely at the college level. Hafley hasn’t coached at the college level since 2011. Mattison will turn 70 this season; Hafley just turned 40.

That pair will head an almost entirely new defensive staff, a group both new to Ohio State and each other. Mattison worked briefly with new linebackers coach Al Washington and assistant secondary coach Matt Barnes and Michigan, but no one in scarlet has worked with Hafley or returning defensive line coach Larry Johnson prior to this season.

The staff isn’t talking much about what they will do, but they’re pretty sure on what they won’t — put so much scheme in the players’ minds that it slows down their feet.

“I wanted them to play confident. I wanted them to have fun. Yeah, we’ve got to work hard and they’re going to work hard and we had to get better fundamentally, and I think we did. Schematically, they had to learn what we were doing… But then, I wanted them to play together, be confident, and have fun doing it. It’s still a game, and those guys have got to have fun. And when they’re doing that with the technique, with the ability, we’re going to be pretty good,” Hafley said of the install process over spring practice.

Ohio State has recruited as well as anyone in the country on the defensive side of the ball. You name it, they’ve got it. Junior defensive end Chase Young is the early favorite to become the No. 1 pick in the 2020 draft.

And yet the product on the field did not reflect the talent of the roster, even despite the 13-1 record, the Big Ten championship, the Rose Bowl victory and the No. 3 final ranking that the 2018 team accomplished. Ohio State was No. 72 nationally in yards per play, No. 50 in scoring, No. 57 in rushing defense and No. 86 in passing defense. You certainly remember the 49 points Purdue dropped on the Buckeyes, but you may have forgotten the 51 scored by Maryland, the 39 by Michigan or the 31 by Nebraska.

With Schiano’s departure and the exchange in personalities from Urban Meyer to Ryan Day, the senior members of Ohio State’s football staff will certainly be less, um, intense in 2019, all with the idea that not loading down the players with scheme will allow their bodies to do the work they were trained to do. (Seriously, listen to Hafley speak and try to not feel at ease.)

“We want to let those guys play really fast, so we tried to not make it very complicated. Now, we can’t be so simple where people are going to scheme us up, but we tried to make it as simple as we could,” Hafley said.

Mattison — who was originally hired as a walk-around coordinator but named himself Ohio State’s SAM linebackers coach because, like Ricky Bobby during a TV interview, he simply didn’t know what to do with his hands after nearly five decades of hands-on coaching — said that if the 2019 Buckeyes are looking wide-eyed with their hands at their sides toward the sideline as the opposing offense approaches the line of scrimmage, he’s done something wrong.

“What ends up happening is all of a sudden (a scheme idea) looks really good to Jeff and I or Al and I and all of a sudden Larry goes, ‘That’s a little too much,’ and you go, ‘Ok, ok, that’s good. Let’s bring this thing back a little bit.’ We have very talented players. Let’s let them play,” he said in June. “Let’s not ever have the thing where they’re looking over (to the sideline) going like, ‘What’s the call?’ As a coordinator, that’s always something I have nightmares about.”

Though the team will look quite different from 2018 to ’19, the expectations are going to be the same. Ohio State was ranked fifth in the preseason Coaches’ Poll, the sixth time in the past seven years the Buckeyes will begin the year in the Top 5 — and they ranked No. 6 in the seventh year. This is Ohio State, perfection is the expectation.

The new Ohio State defense will be a work in progress, but whatever direction the new staff sends its players, they want them to get there with fast feet and clear minds.