The timing couldn't be worse, though.
Maryland (2-1), coming off a 38-10 loss to Central Florida, visits surprising Minnesota (3-0) in its conference opener on Saturday.
The prognosis around the rest of the league is better.
Michigan lost Wilton Speight in the first quarter of a victory at Purdue after being awkwardly on a sack and hit by a second Purdue player in the head or neck.
He left the stadium for x-rays and Harbaugh later referred to it as a "soft tissue" injury. Speight did not return to the game and Harbaugh said he wouldn't play this week if the Wolverines (4-0, 1-0 Big Ten) had a game.
But Speight's injury led to two midweek debates: One about locker room conditions around the conference, the other about a hit Harbaugh described as "egregious."
"If I had a stronger word to use, I would use it," he said. "With all the emphasis on protecting defenseless players, it appeared that the player knew what he was doing. He targeted the head. (Speight) was on the ground, and he accelerated."
No penalty was called, though two Purdue players were ejected for targeting in the second half.
Without Speight, the Wolverines rallied behind former Houston quarterback John O'Korn who could start against Michigan State on Oct. 7.
Not surprisingly, Boilermakers coach Jeff Brohm took exception to both complaints.
"I didn't see anything egregious about it," he said. "I thought he made the tackle. I don't think there was a flag on it was there? From my standpoint, I thought it was a clean hit."
He also didn't appreciate Harbaugh's contention that Purdue's locker room was unsanitary or the exam tables looked like something out of the 1920s.
Purdue (2-2, 0-1) even issued a statement, noting it informs teams about the lack of air conditioning at Ross-Ade Stadium.
"I know a lot of the visiting locker rooms across the country are not like going to the Marriot hotel, they don't have a lot of frills," Brohm said. "I haven't been in a lot of locker rooms that have been extremely nice and comfortable for the visiting team."
Brohm was more concerned with his own quarterback's health. David Blough sprained his throwing shoulder in the second half last weekend, aggravating an injury he first sustained in August. He also did not return, and Brohm declined to say whether he expected Blough to play against the Golden Gophers next week.
"He will be limited this week," Brohm said. "We're hopeful he can practice next week with us."
Indiana quarterback Richard Lagow's lower leg injury looks like the least serious of the four injuries.
He was hurt taking a big hit on his only touchdown pass of the game.
Coach Tom Allen said he could have returned — if the Hoosiers (2-1, 0-1) hadn't built such a large lead over Georgia Southern. So they held him out, hoping Lagow will be healthy enough to start at No. 4 Penn State (4-0, 1-0) this weekend.
While each of the four teams is adapting, all four know there's only one way to move forward.
"These are all guys who have been practicing and preparing, you can go through the process of the game plan and what you're calling, what they're comfortable with, what they're not," Durkin said. "I think a week is plenty of time to get that done."