Allen remained motionless on the turf for a few moments early in the fourth quarter following a helmet-to-helmet hit from Patriots safety Jonathan Jones, who was flagged on the play but not ejected. Matt Barkley nearly led a scoring drive on his first series but threw an incompletion on fourth down from the Patriots 3-yard line.
The Bills officially placed Allen in concussion protocol after the game.
Prior to his injury, Allen completed 18-of-39 passes for 153 yards and three interceptions. He also ran for a touchdown.
There was a certain amount of disbelief in the Bills locker room that Jones, whose penalty was offset by an offensive holding call, wasn’t ejected.
Buffalo has no other quarterback on its 53-man roster, but signed Davis Webb to its practice squad in Week 1.
Jones told reporters after the game the hit was not intentional and he would check up on Alan to make sure he was OK.