Cassel was released by the Titans on Friday, Ian Rapoport of NFL Network reports.
Cassel was horrific in his one fill-in start last season, throwing for 4.4 yards per attempt in a 16-10 loss to the Dolphins in Week 5. He'll turn 36 in May and may need to compete for a backup job if he decides to continue his career. The Titans are left with Brandon Weeden, Alex Tanney and Tyler Ferguson behind Marcus Mariota. The team likely will seek a backup QB upgrade in free agency or the draft.