For much of the Michigan football season, the Wolverines featured a highly ranked, elite defense. Three straight shutouts in the middle of the season, seven opponents held to 235 total yards or less.

But in their other five games — losses to Utah, Michigan State and Ohio State and last-second or overtime wins over Minnesota and Indiana — they were vulnerable on defense.

The Utah, Michigan State and Ohio State games stung the most because the offense didn’t have enough to bail them out.

Each time the simplest element became the biggest challenge for the defense, one the Wolverines have to fix before facing Florida in the Jan. 1 Citrus Bowl.

“Tackle,” U-M co-captain and linebacker Joe Bolden said earlier this month. “When you look at both (MSU and OSU) games, we didn’t tackle well at all. Having a month to go out and practice hopefully we get to tackle some guys, tackle scout team guys, and with the luxury of time we’ll be able to go I’m assuming against one another, one on ones. I think that’ll help with the tempo and everything.”

The most frustrating part for the Wolverines was that earlier in the season, against Utah, MSU and Minnesota, the opponent’s passing game beat them and then, in two of the final three games, against Indiana and Ohio State, it was the opponent’s running game.

Entering the Indiana game, U-M had one of the best rush defenses in the country, not allowing any team more than 144 yards.

Then Indiana’s Jordan Howard ran up 238 of the Hoosiers’ 307 yards.

That might have been just an aberration that appeared fixed when Michigan next shut down Penn State, allowing one long run on the first drive, then just 14 yards the rest of the game.

But Ohio State showed that U-M’s run defense was a real problem, as the Buckeyes rushed 54 times for 369 yards in the season finale. Michigan could not stop the combo of tailback Ezekiel Elliott (214 yards) and quarterback J.T. Barrett (139 yards), both averaging over seven yards per carry in OSU’s read-option offense.

“I don’t think it’s just one thing — obviously tackling is a big part of it,” U-M senior linebacker Desmond Morgan said. “We had quite a few busts going on, in terms of guys not fitting things right, which is disappointing because we had good practice. Granted, you can’t practice everything a team is going to show — they hit us on a few things we hadn’t practiced for. But also we had some new guys in there that hadn’t been playing as much. I don’t want to put that as an excuse, but it’s reality in some ways.”

Due to injuries and lack of production, U-M didn’t rotate as much as other games on the defensive line against Ohio State. So the month of rest and practice should help, even if two starters from the first half of the year — nose tackle Ryan Glasgow and defensive end Mario Ojemudia — won’t be back from their injuries.

Though Florida’s offense has struggled, especially late in the year with only one touchdown in its final two games, the Gators have ground potential with NFL-bound tailback Kelvin Taylor (985 yards and 13 touchdowns) and dual-threat quarterback Treon Harris, who has 183 rushing yards despite starting only the second half of the season.

And U-M has a new defensive coordinator, Greg Mattison. The defensive line coach this year under coordinator D.J. Durkin, Mattison took over the job for the bowl practices and the game after Durkin left to become Maryland’s head coach. Mattison was U-M’s defensive coordinator the previous four seasons.

“We’ve been making some adjustments,” U-M coach Jim Harbaugh said on his radio show Tuesday. “Greg Mattison is doing a heck of a job, a great football coach. There’s some things that we’re changing, making some adjustments to and I think we’re going to be better for it. People are asking me during the break how things are going, practice has been outstanding.”

It helps that Mattison is familiar with this veteran defense.

“I have full confidence in Coach Mattison,” Bolden said. “Four years ago when I committed here I had full confidence in him then. He’ll have us ready, he’ll have us ready to defend whatever they’ve got for us. Whether it’s read-option or downhill more pro-style inside run game.”