Charles Walker Leaves Oklahoma to Pursue 2017 NFL Draft: Details, Reaction

Oklahoma junior defensive lineman Charles Walker has reportedly decided to leave the Sooners effective immediately to begin preparations for the 2017 NFL draft.

Ian Rapoport of NFL Network first reported the news, noting Walker alerted OU head coach Bob Stoops about the decision.

"Quitting on your teammates is hard to take as a coach," Stoops said, per Ryan Abner of the Oklahoman.

Walker tallied seven total tackles, four passes defended and two quarterback hurries across four appearances for the Sooners this season.

His status had come into question over the past few months, however. His last game was a victory over TCU on Oct. 1, when he suffered a concussion.

Brooke Pryor of the Oklahoman noted in October the defensive tackle posted a message on his private Twitter account downplaying rumors he was potentially leaving the program: "I'll never leave my guys behind if I wasn't able to .... period."

His health had become a concern, though. The head injury suffered against the Horned Frogs was his second concussion over the past year. He missed the Orange Bowl with one, as well. The lineman also underwent wrist surgery in April. Those issues may have shifted his outlook toward a quicker NFL jump.

In August, Joe Buettner of the Oklahoman passed along comments from Walker about trying to make a better life for his two-year-old daughter, whose birth completely changed him: "I was a totally different guy than what I am today," he said. "I didn't have the drive I have now, the ambition, the heart I have, how mentally I am now. Having a daughter really changed me."

How the decision to leave school now will impact his draft stock isn't clear. CBS Sports listed Walker as the No. 91 overall prospect and the ninth-best defensive tackle in the 2017 draft class before the news.

Meanwhile, the Sooners have gone unbeaten since Walker's injury forced him from the lineup. Jordan Wade, Austin Roberts and Neville Gallimore will continue to lead the defensive front following Walker's official exit from the team.