Published: Aug 06, 2012 5:21 PM EDT
Updated: Aug 07, 2012 6:31 AM EDT

NORMAN, Okla. (AP) - Oklahoma coach Bob Stoops is staying positive even as training camp has brought a series of unfortunate twists.

Starting offensive guard Tyler Evans was getting an MRI on Monday to determine the extent of a knee injury he suffered at the start of camp, yet another blow to a Sooners squad that was already going to be without five other players for the upcoming season.

Stoops revealed after Monday's practice that Evans was running down the field during the Sooners' first practice of training camp Friday when he was hurt.

"It may be a ligament. It may be cartilage," Stoops said before the MRI was performed. "If it's cartilage, he gets a break - or we get a break. If it's not, then it could be bad. Until you get the MRI, you don't know."

Evans is Oklahoma's most experienced lineman left after starting center Ben Habern gave up the sport just last week because of lingering neck and back issues. Evans, a senior, has 29 career starts and has been in the lineup for the past 13 games in a row. Habern, another senior, had started 30 games.

"It's a couple of tough breaks but we've still got guys in there that we really like," Stoops said. "I bragged about Bronson Irwin all winter and spring. I can tell he's in great shape here this summer. He must have did a great job. He'll have to really step up. But yeah, it makes you a little more thin."

In part because of Habern's broken arm last season, the interior offensive line appeared in the offseason to be one of the deepest spots on the team. Gabe Ikard had moved over to center, and Adam Shead had replaced Ikard at guard. All of the group - plus Evans - was returning.

Now, the hits are starting to pile up along the line.

Lineman Will Latu was one of two junior college transfers, along with receiver Courtney Gardner, who didn't make it into school and reserve lineman Dylan Dismuke suffered a career-ending injury.

On Monday, Stoops said incoming freshman John Michael McGee was given the day off from practice because he was feeling homesick and needed to decide whether he wanted to play.

At this point, the middle of the line will likely feature Ikard at center with Shead, a sophomore, and Irwin, a junior, at guard.

"It's an opportunity for the next guy, whoever it is. ... They're working hard," said James Patton, who coaches the guards and centers. "It happens now. At least we plan for those things. If it happens late in the season, we've got to have a plan for that."

Some good news could be on its way. Receiver Justin Brown, who left Penn State, is expected to join the Sooners although Stoops said he couldn't comment on the situation because Brown hasn't signed any scholarship paperwork at Oklahoma yet.

Stoops refused to let all of the negative developments get him down.

"Every year when you're dealing with 105 guys, you're going to have some of that," he said. "Who doesn't? Everybody gets a guy hurt, everybody has a guy quit, everybody has a guy transfer. I don't think we're much different than about anyone else."

For him, the bottom line was this: "I don't see anything here so far that should hold us back very much."