Oklahoma defensive lineman Charles Walker has decided to immediately leave the Sooners to prepare for the NFL draft, the school confirmed Tuesday.
Walker started four games for the Sooners this season before suffering a concussion Oct. 1 against TCU. He has not played since.
"Quitting on your teammates is hard to take as a coach," Oklahoma defensive coordinator Mike Stoops told reporters after Tuesday's practice.
Walker was a second-team All-Big 12 selection last season after racking up 36 tackles, including 10 for loss, and six sacks. However, he missed the Orange Bowl against Clemson, due also to a concussion.
ESPN draft analyst Mel Kiper Jr. recently ranked Walker the No. 6 defensive tackle eligible for the upcoming draft.
Oklahoma has two games remaining in the regular season, against West Virginia on Saturday and Oklahoma State on Dec. 3. The Sooners are 8-2 and first in the Big 12 standings.
