Coach Romeo Crennel said Tuesday that doctors have not cleared Quinn to practice, so Cassel will be the starter and Ricky Stanzi the backup. Cassel was the starter the first five games of the season before he sustained his own concussion against the Ravens.
Quinn started one game in Cassel's place, and then Crennel made the switch permanent going into last Sunday's game against the Raiders. Quinn was hurt late in the first quarter, and Cassel played the rest of the way in a 26-16 loss.
The Chiefs (1-6) have lost four straight games.