I agree with two main points made earlier- Aberration and MMs ego.
We suffered a lot of injuries, but no one stepped up. It seemed instead of stepping up to make a play we took turns stepping up to make a mistake; penalty, drop, fumble, missed tackle. Instead of finding rhythm we'd find fail. We always seemed to find a way to stop ourselves. NO ONE played as good as they could. Even Crosby, he had a great year but found a chance to fail (Detroit) too.
The biggest obstacle, IMO, was MMs ego. His decisions of not adjusting to personnel available is frustrating. The choices the coaching staff made along the OL were mind numbing, especially the last minute choice of Sitton at LT! I think that was a big factor in ARod's uncomfortableness (is that a word?). Sitton at LT, Barclay anywhere but RG, ugghhh. Lastly on MM. I think Nerd said it best: Fear based coaching late in big games. The "Play not to lose" theory. It kills us, especially in the playoffs.
One last point I'd like to make: Blaming Randall for that last big play in OT vs Cards is silly. It was the forty missed tackles after the 6 yard pass that blew it. How many guys took the wrong angle, dove at shadows or just plain quit on that play. It was a total team brain fart.