The Bengals lost a key cog in their offense Sunday when running back Joe Mixon exited in the second half against the Steelers with a concu sion.Mixon, who was initially ruled questionable to return after leaving the game, was ruled out following an examination. He will now have to pa s the NFL's new concu sion protocol to return to the field.MORE: Mixon left the game in the third quarter.. Injury Update: HB Joe Mixon has been declared out with a concu sion. Cincinnati Bengals (@Bengals) He finished Dak Prescott Jersey with seven carries for 20 yards and three receptions for 42 yards in the Bengals' first game since his five-touchdown outburst (four rushing, one receiving) against the Panthers.Mixon has 158 carries for 605 yards and six touchdowns for the season. He also has 41 catches for 314 yards and two scores.MORE:If there is a silver lining for the Bengals, backup Samaje Perine got into the mix in the pa sing game with a pair of touchdown receptions.The Bengals will face the Titans in Week 12. Deion Sanders Jersey Mixon will have to clear the protocol with an indepedent neurologist if he is to see the field for that game.