One could argue that, despite the playing-time disadvantage, Pryor still failed to separate himself from Flynn. As noted in slide above, Pryor still had an opportunity to make a move up the depth chart with a quality performance against Seattle. But instead he completed fewer than half of his passes and was intercepted once.
Since the time Flynn was acquired in a trade, the starting quarterback position has seemingly been his to lose, even if nobody within the Raiders officially declared him the starter.
The playbook that new offensive coordinator Greg Olson brought to Oakland consists of mostly short timing routes—plays designed to benefit a passer like Flynn, whose arm strength is nothing exceptional.
Starting Pryor in Week 1 would put him in a scheme that wasn't designed for him. But Pryor's stronger arm could still stretch the field and present more big-play opportunities than if Flynn were under center.
Pryor has been an underdog on Oakland's depth chart since he was drafted by the Raiders in 2011. The Raiders have done seemingly everything to not start him in a meaningful game. His lone start came at San Diego in Week 17 last year, when the Raiders were merely playing for their spot in the draft and bragging rights against their division rivals.
Pryor played a very average game at Seattle, and considering how much the Raiders brass has tried to bury him behind Carson Palmer and even Matt Leinart (who started Week 16 last year), it would have taken a much stronger showing from Pryor to cement himself as the Week 1 starter.