Coach Sean McDermott confirmed Monday that Allen is in the league's concussion protocol, Chris Brown of the Bills' official site reports.
This was expected and even confirmed by other sources Sunday night after Allen took a shot to the head during the loss to the Patriots. Typically, players have to pass every step of the protocol on schedule to play in the team's next game if it's seven days away, and in the Bills' case they take on the Titans this Sunday. Matt Barkley would take over for Allen if that doesn't happen, while it's worth mentioning the Bills have a bye following the Titans game.