This idea that people are ready to just write off a guy because he had a bad season is short-sighted. Past examples, regardless of the actual similarities in the situations, indicate that the future doesn't have a defined path, and that maybe, just maybe, the guy might be able to improve from year to year.
This whole Mangum vs Wilson vs Critchlow garbage that has clogged up the board is just fans showing a lack of understanding of the nuances within the game. In reality, it doesn't matter who starts if they win games. The coaches will choose the person they feel gives them the best chance at that. Their livelihood rests on this decision, so it stands to reason that they might put a great deal of thought, drawing on their decades of experience in this realm, to try to make an informed decision. I don't know how much I really trust the coaching staff, but that's a different discussion. Regardless, they will make the best choice, and the team will hopefully win a lot of games.