Purdue beat Ohio State by 29 points. The Gophers, who a week earlier lost to Illinois by 24 points, beat Purdue by 31 points.

Go ahead, just try to figure out this Gophers football season.

“It’s been a roller-coaster year,’’ coach P.J. Fleck said, and that was even before his team went out and dominated Purdue 41-10 on a snowy Saturday at TCF Bank Stadium.

That roller coaster is climbing right now, and that’s mostly because of what happened with the Gophers defense. Minnesota (5-5, 2-5 Big Ten) hit its low point of the season so far in that 55-31 loss at lowly Illinois, and that prompted Fleck to fire defensive coordinator Robb Smith and replace him on an interim basis with defensive line coach Joe Rossi.

Fleck’s message to Rossi and his charges was to play “sound, simple, fast,’’ and from the start of the game, it was apparent that the defense was different.

Purdue got its initial first down on its first possession, but nothing more. And when the Boilermakers intercepted a pass and took over at the Minnesota 38-yard line in the first quarter, the Gophers defense allowed only Spencer Evans’ tying 40-yard field goal.

For the rest of the first half as the Gophers built a 13-3 lead, Purdue’s possessions went three-and-out, three-and-out, a fourth-down turnover on downs and one 18-yard drive. Aside from that interception, the Boilermakers never made it to Minnesota territory in the first half. Purdue finished 0-for-12 on third-down conversions.

“We didn’t change our defense,’’ Fleck said. “The defense is the defense, and the defense works. We got back to [being] us.’’

That certainly applied to a pair of Gophers linebackers who struggled in the loss at Illinois. Senior Blake Cashman, the team’s leading tackler, had only four tackles against the Illini, and junior Thomas Barber, the team’s No. 2 tackler, had only one stop.

Against Purdue, Cashman led the Gophers with nine tackles (seven solo), had a half-sack and made a fourth-down tackle for no gain. His signature moment came early in the third quarter, when he sniffed out a run by Boilermakers quarterback David Blough, knocked the ball from him, scooped it up and returned it 40 yards for a touchdown and 20-3 lead.

“I’ll be honest, Blake Cashman had the worst game of his career last game,’’ Fleck said. “I don’t say that like I’m picking on him. I told him that. He told me that. That just shows the resolve this team has.’’

Said Cashman: “I was frustrated with my performance [at Illinois]. I thought it was unproductive. But what we talk about in this culture is responding.’’

Barber, too, responded with eight tackles (five solo) and 1 ½ sacks. “Execution was much higher than last week,’’ he said. “We were out there flying around and having fun.’’

Who wasn’t having fun on the 21-degree day was Purdue. As the snow began falling a bit harder after halftime, the Gophers stretched the lead to 34-3 in the third quarter. Purdue coach Jeff Brohm admitted his team wilted in the weather.

“I don’t think we were ready for the elements,’’ Brohm said. “We let that get to us.’’

Minnesota’s suddenly resurgent defense made sure of that, and Cashman credited Rossi for setting the right tone.

“We had a simplified game plan, which allows guys to play loose, play fast and gives them confidence,’’ he said. “We lost some of that against Illinois when they came out and hit us in the mouth early.’’

The Gophers finish this roller-coaster season with a home game against Northwestern and a road trip to Wisconsin. Cashman sees a chance to build off Saturday’s result.

“Being honest and real with ourselves, we’ve seen we can play at a such a high level,’’ he said, “but we’ve also seen we can lay a goose egg and get blown out by teams.’’


Randy Johnson covers college football for the Star Tribune. Twitter: @RJStrib E-mail: rjohnson@startribune.