If they lose, it’s always due to something other than obvious poor team play (like 5 turnovers in a game). Other excuses include:

Jared Allen’s hair conditioner went missing before the game.
For his pregame meal, Favre was given the wrong brand barbecue sauce.
Brad Childress had a roid flareup.
The refs had to pay for their own Metrodome parking and thus took it out on the team by making bad calls against them.
There was a mudslide in southeastern Nepal.
An asteroid collided with Jupiter.