OKLAHOMA CITY -- Oklahoma State starting quarterback J.W. Walsh will miss the rest of the season after hurting his knee in a 31-10 victory over Iowa State on Saturday, the latest blow in an injury-marred season.

Coach Mike Gundy said Sunday night that he believes Walsh was hurt within the first 10 or 20 plays of the game but never complained or came out of the game with the injury that will keep him out for the rest of the season.

Walsh ended up throwing for a career-high 415 yards and running for 46 more in the win. He threw for one touchdown and ran for another, in the fourth quarter. Gundy said the injury was not career-threatening.

"He finished the game. He ran, made throws. I'm speaking a little bit out of turn because it wasn't an injury that progressively got worse. It just happened and then he was able to play with the pain," Gundy said.

"I can only say that it was a pretty amazing performance. I would hate to use that term for a guy or a player on my team that's only a freshman, but for him to finish the game the way he did and run the football and never say a word was really a terrific performance."

Walsh inherited the starter's job after freshman Wes Lunt was hurt in the third game of the season. The two had competed with Clint Chelf for the opening during the spring, after Brandon Weeden was taken in the first round of the NFL draft, with Lunt winning the job.

Gundy said he thinks Lunt will be able to start Saturday against TCU, but the Cowboys "haven't figured that out yet."

Oklahoma State also lost tight end Justin Horton to a season-ending injury. Receivers Tracy Moore and Isaiah Anderson missed last week's game against Iowa State and backup running back Jeremy Smith was limited. All had injuries that were not disclosed under the Cowboys' new, more restrictive policy.

"I just hate it for them because coaches, this is our life and we understand and we deal with these situations. But it just tears you up inside when you have to see a young man working their tail off get put in those situations," Gundy said.

"As a team, we're fine. We rally, other guys play and we keep rolling. But it's just a heartbreaker for a coach when you see a young man that's out for the year."