I keep thinking about Tom Brady who won the Superbowl his first year as a starter. They got close when he was back up the year before but fell short and the next year they were in the superbowl. That sounds just like what happened with us but the end result has yet to be seen.
Just because Chico is unproven though an entire season doesn't mean that we have to take a step backwards. There are 52 other men on that team and though I am not sure the exact number, I know a majority of them where on the team last year. Favre wasn't the only tallented member of the team last year so we still have the vast majority of our tallent around our somewhat raw and unproven quarterback. Just like the Pats did back when Brady started. And look what has happened to them: 3 or 4(I can't remember) super bowl wins and an 18-0 season before loosing in a very hard fought(in the 4th quarter) battle.