First, it was center Ben Habern. On Monday, the Sooners lost senior guard Tyler Evans for the season.

Evans injured his right knee in practice on Friday and an MRI on Monday revealed a torn ACL. Between Evans and Habern, who had to end his career because of lingering back and neck injuries, the two seniors had 59 starts between them.

The Sooners will turn to junior Bronson Irwin to replace Evans. Irwin has not started before; he played 127 snaps last year.

"He's a capable starter," offensive line coach James Patton told the Oklahoman. "He plays hard. He's a great kid. He had a great winter and a great spring, and it looks like he carried it over."

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The Sooners open the season with a UTEP on Sept. 1. The Miners had 24 sacks last season. OU quarterback Landry Jones is still confident in his protection.

"They were so deep all the way around," Jones said. "So, yeah, we lost two really dominant players, but we're still pretty set at those spots."

Other news and notes around the Big 12

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  • TCU right tackle James Dunbar did not practice because of academic issues as TCU opened camp on Monday. Dunbar, who is listed as a starter in TCU's media guard, also missed the beginning of last season because of academic problems.
  • New West Virginia defensive coordinator Joe DeForest is emphasizing forcing turnovers. DeForest coached safeties and special teams last year at Oklahoma State, where the Cowboys led the nation in takeaways.
  • In the spring game, Kansas was so thin on the defensive line that the players on the d-line played for both teams. Coach Charlie Weis added two impact players and good depth with two transfers: Josh Williams, a defensive end from Nebraska who is a fifth-year senior, and defensive tackle Keon Stowers, who played last season at Georgia Military College.
  • Nice profile of K-State quarterback Collin Klein in the Sporting News. Klein and the Wildcats are the underappreciated in the Big 12. Will they be able to turn that into motivation for a another climb up the standings? 
  • Defensive end Alex Okafor, safety Kenny Vaccaro and tight end Barrett Matthews are back in the good graces of Texas coach Mack Brown. All three were arrested in May for an incident outside an Austin pizza shop.
  • A Q&A with Oklahoma State center Evan Epstein. Epstein, a senior, should be a big help to freshman quarterback Wes Lunt.
  • Texas Tech coach Tommy Tuberville said he liked his team's energy during the first day of practice on Monday. Tuberville has had nothing but good things to say about his team throughout the preseason.

For more up-to-the-minute news and analysis from Big 12 bloggers C.J. Moore and Patrick Southern, follow @CBSSportsBig12.