I know it's asking a lot to say, "Brett, this could be the last shot you've ever got, don't trip over a rock near the finish line" (using your analogy), but to me, I felt that he was given a big leash for a long time with the organization, again under the premise that he would be the "x factor" when we needed it. He was given the chance to carry the team on his shoulders, and I wouldn't quite say he failed, but he also obvioulsy didn't lead the team to the SB when we needed him to.
And I don't think he was 'punished' for this, but I also think that the packers were in a bind with Rodgers...1 year from a contract year, and if brett comes back, he rides the pine again, and could very well want to leave after that. Brett had proven over the previous 5 offseaons that at any point he's liable to retire, so all you've got is an aging unreliable QB (based on retirement talk) who couldn't lead the team at crunch time, didn't necessarily screw them, but again, no SB appearance with game on his shoulders...and then maybe the future QB, maybe a dud, sitting on the sideline, who is subject to leave if you don't give him a shot.