Super Bowl contenders: are the NFL’s unbeaten teams as perfect as they seem?

The early standouts have emerged. But even the best teams have flaws that can be exposed by their opponents

Who would have thought the 49ers would be here after a rough old offseason? Head coach Kyle Shanahan's participation in training camp was limited due to a serious car crash, team owner Jed York's visit to an Ohio trailer park did not end well, and one player after another endured serious injuries. Despite all this, San Francisco are full of positive vibes. They are top of a tough division and their immense defense, led by the intensity of players such as safety Malik Mustapha and Fred Warner, is complemented by an equally impressive offense.