Colorado State defensive coordinator Tyson Summers was fired amid Saturday's 56-26 loss to Oregon State, coach Jim Mora announced after the game.
Summers was replaced as playcaller by assistant Kenny McClendon during the first half of Saturday's game. A source told ESPN's Pete Thamel that Summers wasn't fired during the game.
"Tyson was relieved of his playcalling duties," Mora told reporters afterward. "He left the field and he's no longer with this football program."
Summers was spotted on the sidelines earlier in the game, which was Colorado State's Pac-12 debut. The Rams have surrendered at least 41 points in their past three games, all losses.
Summers had been Colorado State's defensive coordinator since 2025. After the Rams fired head coach Jay Norvell last year, Summers severed as Colorado State's interim coach for five games.
After taking the job, Mora retained Summers as his defensive coordinator.