That's because their defense doesn't step up. There's not a lot Bulger can do.
And I agree with Tony about the Niners' success depending on Alex Smith. But I think it will depend more on him being able to manage the game and not lose it rather than going out and having to win it. The running game should put them in position to score, Alex just needs to make sure he plays smart and doesn't blow the game. I think he did a decent job of that last year, but the defense was ass until the end of the season so they lost some games they should have won. This year the defense should be a lot better.