The Bills announced QB Matt Barkley will start against the Jets on Sunday.
The 28-year-old former USC product was signed by the Bills on Oct. 30 as insurance and has not played a down in the NFL since 2016.
Nathan Peterman is the only other healthy quarterback the Bills have with Derek Anderson out with a concussion and Allen is questionable with a sprained right elbow.
But Peterman has been dreadful, throwing just one touchdown to seven interceptions in four games this season.
When Bills head coach Sean McDermott was asked about Peterman starting, he said he prefers to keep the focus on Allen -- whose status is still uncertain.
It was a different tune from earlier in the week, when McDermott said Peterman would start if Anderson and Allen could not play.
Barkley's career numbers are not much of an upgrade over Peterman. He has eight touchdowns to 18 interceptions in 11 career games with the Eagles and Bears.
Regardless of which quarterback starts, the Jets defense may be in for a big day.