Pryor sat out last week's 24-14 loss to the Redskins after suffering a concussion the week before against the Denver Broncos.
Pryor has completed 65.4 percent of his passes for 624 yards with two touchdowns and two interception this season for Oakland (1-3).
"It is what it is. It didn't work out," Allen said about Flynn's demotion. "It hasn't worked out like we anticipated and we've got to make decisions and we've got to move forward and continue to go, and [Flynn is] going to continue to battle and scratch and claw, and I still believe that he's a capable quarterback. But we're going to give McGloin a chance."