Cassel, who'll be 36 when the season starts, broke into the NFL with the Patriots in 2005, backing up Tom Brady for four seasons before taking over as the Kansas City Chiefs' starting signal-caller. After stops in Minnesota, Buffalo and Dallas, Cassel spent the past two seasons with the Tennessee Titans behind Marcus Mariota.
Cassel provides a high level of been-there experience to the Lions' passer corps even if his best days might be far behind him. He struggled in his last real game action, which came in seven starts in place of an injured Tony Romo while with the Cowboys in 2015. In Tennessee, he appeared in six games and went 1-1 in two starts.
It's been more or less downhill for Cassel since 2010 when he led the Chiefs to a 10-6 record and an AFC West crown after passing for 3,116 yards and 27 touchdowns. Still, it appears Quinn is comfortable giving a player from his Patriots past a chance to backup a quarterback who hasn't missed a start in more than seven seasons.