The Buckeyes have shown marked improvement since and have a few factors to thank.
From a personnel standpoint, the lineup Ohio State defensive coordinator Luke Fickell and co-coordinator Everett Withers can put out there now is different in more ways than one.
Nathan Williams, a senior defensive end, missed the debacle in Bloomington with a concussion but has returned to provide a stabilizing force at not only his natural position but also linebacker at times.
Barnett missed three games with a sprained ankle prior to facing the Hoosiers, and his rustiness was apparent in his first game back.
He had nothing on Boren when it comes to time away from the defense, though. A senior who started the last three-plus seasons at fullback, Boren returned to his high school days when he took over at middle linebacker against the Hoosiers. He posted eight tackles that night but admitted he was still in an adjustment period.
Fast forward three weeks, and it is clear the unit is playing better in most phases.
The Buckeyes trimmed 18 yards per game off what was the conference's worst pass defense (down to 259.7 yards per game). They showed a similar improvement on the ground, where the average rushing yards have dropped from 122.3 to 107.9. The latter total is good for 16th in the nation and No. 1 in the Big Ten with two games remaining in slate.
The scoring average has seen only a modest improvement, dropping from 24.6 points to 23.9, but that is in part due to a non-offensive touchdown in each of the last three games.
So what is the difference?
Communication, execution, confidence and familiarity, to name a few things.
"I think everyone is communicating and understanding the deal," Withers said. "I think our kids in the back seven are starting to understand when we get this formation these are the two or three things that are happening and improving with that.
"Everybody recognizing exactly what they need to see in that formation and understand what's happening."
That has been instrumental in cutting down on one of the biggest issues the defense faced – big plays. After allowing 30 plays of 20 yards or more (20 passes and 10 runs) in the first seven games, they have allowed only seven in the last three. All of those have been through the air, and none came in the past game, when Illinois' longest gain from scrimmage was 12 yards.
Communication is key as the secondary adjusts to playing "quarters" coverage, a scheme that offers a lot of versatility but can be tricky as all four make their own reads in the back end.
"They have an understanding of it," Withers said. "Our kids know it. We really emphasize it in practice, and I think they're getting better at it.
"Any defense takes time in the back end. Guys have to communicate well and I think they're continuing to get better with that. The more we communicate, I think the better we'll be."
The return of Barnett and the development of freshmen defensive linemen Noah Spence, Adolphus Washington and Tommy Schutt has helped as well. Barnett gives the team another player capable of matching up with a receiver while the young linemen can get after the quarterback and provide a more athletic look up front. That also frees up Williams to move around the line to get the team's best pass rushers on the field together.
Those developments also allow the staff to mix and match a few more coverages.
While that has not yielded more sacks, it has created better pressure and made throwing downfield more difficult.
"We're mixing in some more man-to-man, some more pressure," Withers said. "We're trying to figure out more ways to get after the quarterback. Sometimes when you play running quarterbacks it's hard to blitz them because a lot of times you don't account for that quarterback in the blitz. When they motion out of the backfield and do a lot of the things (Illinois) tried to do today, they were trying to limit us from pressuring them. We had some things we could have gone to, but we felt like we were good today so we didn't need ‘em."
The evolution of the personnel – something that could continue if senior linebacker Etienne Sabino is able to return from a broken leg when the Buckeyes head to Wisconsin for their next game – is not the only contributing factor. Growing familiarity within a coaching staff that is 50 percent new on the defensive side of the ball – Withers and cornerbacks coach Kerry Coombs came on board earlier this year to join Fickell and defensive line coach Mike Vrabel – has made crafting game plans easier, too.
"We've put in a lot of different game plans and what's so unique now is we're able to pull from different game plans now and say, ‘This was good for us. What do you think about this?' " Withers said. "That first year is always a year you're trying to get on the same page and work through different philosophies and though processes. I think as the year goes on we continue to get better at that."
Schematics aside, players such as Ryan Shazier admitted a pep talk from head coach Urban Meyer following the Indiana game has played a role in the defense's improvement as well.
"It was a really intense meeting and everybody knew that they weren't doing what they were supposed to do and we changed it around," said Shazier, the team's leading tackler and a sophomore on the rise.