DALLAS — Losing to its arch rival, losing its middle linebacker, losing total control of the Big 12 and national championship race would make most think the only thing that’s taken a bigger crash than Oklahoma is the stock market.

But the sun still came out Sunday, one day after the Sooners’ 45-35 loss to Texas at the Cotton Bowl in Dallas.

“It’s always disappointing to invest so much and you end up losing,” OU coach Bob Stoops said. “…You just watch everyone else play, it isn’t that easy to go undefeated at all. There’s a ton of games left. There’s half the season left, and a lot of good teams out there. We’ve got to be ready to play to be at our best. Chances are everyone else could have the same thing happen to them. I don’t need to refresh everyone’s memory. The national champion a year ago had two losses. And late in the year. There’s a lot of football left.”

The Sooners (5-1, 1-1 Big 12) have reached the midway point in the regular season. The loss, at least in the polls, wasn’t crippling. They fell to No. 4 in the Associated Press poll. They came in at No. 6 in the USA Today coaches poll and No. 4 in the Harris Poll. The last two are most important — they are the components in the BCS standings.

OU has established itself as the highest-ranked one-loss team in one and second (behind USC) in the other.

But keeping a high ranking does nothing to mask two huge problems it faces on both sides of the ball. There’s isn’t much time to find solutions either. Next up is No. 16 Kansas (5-1, 2-0 Big 12) at 2:30 p.m. Saturday at Owen Field.

The first issue is what the Sooners will do at middle linebacker now that Ryan Reynolds will miss the rest of the season due to a knee injury.

Texas took over the game after Reynolds limped off the field early in the third quarter. Twenty-four of the Longhorns’ 38 offensive points came after Reynolds’ injury. Most of those yards came on run plays, scrambles by quarterback Colt McCoy and short to intermediate passes over the middle. Reynolds could have affected just about all those plays.

Both Stoops and defensive coordinator Brent Venables said there will be an open competition to see who steps into the job. Redshirt freshman Austin Box is the most obvious choice. He was penciled in as the starter at weakside linebacker in the preseason, but a knee injury and Travis Lewis’ emergence dropped him down on the depth chart. Mike Balogun and Brandon Crow, who filled in for Reynolds against Texas, also are options.

“Austin is not ready to be declared the guy,” Venables said. “You have to go out there and earn it. It will be whoever is most consistent and who can make the plays that position requires you to make.”

Another option is to move Lewis to the middle spot. But he just made 19 tackles against Texas and is playing at an incredibly high level. Moving him could mess that up.

But that’s the defense’s issue.

OU’s failure to run the ball (28 carries for 48 yards) couldn’t be placed on the absence of a player. It was a fundamental breakdown throughout the offense.

Offensive coordinator Kevin Wilson isn’t pointing fingers.

“We need to be a better run team. We’re not trying to be a finesse team,” offensive coordinator Kevin Wilson said. “If the run game is not going, I have to make it work and give us a chance to win.”