Oklahoma State has fired defensive coordinator Glenn Spencer, the school announced Thursday.
Spencer first joined Mike Gundy's staff in 2008 as a defensive line coach. In 2013, he was promoted to defensive coordinator and that season was nominated for the Broyles Award, given to the nation's top assistant coach.
Under Spencer, the Cowboys ranked 53rd, 93rd, 100th, 92nd and, this season, 79th in total defense.
In a statement released by the school, Gundy said, "I'm very appreciative for the 10 years of loyal service that Glenn Spencer gave to Oklahoma State."