I like to think of things in the football world as being a sort of "closed system" that has at its top a set of football gods who determine luck, fate, and so forth. They ensure order and fairness in competition.
Last season, I would assume that the football gods were not happy with the Patriots and their smug behavior. Then came Brady's "We're only going to score 17 points? (smug laugh)" followed by his withdrawl from the Pro Bowl, which showed a sense of poor sportsmanship.
They smote him with the loss in the game, and with this mysterious injury during the preseason. But, they took it a step further and saw to it he won't play again this year.
I can't say I'm sorry to hear that, though I don't wish ill on anyone. The football gods did what they had to.