Sad story the Giants are, one season they beat the Patriots and get the super bowl then they go downhill fast.
That's the NFL for you. Take a look at the Steelers. They won the Super Bowl last year and they have less wins than the Giants now. It's very common for a team to appear in the Super Bowl and then have a bad season the very next year, for example, the Bears, Cardinals, and Seahawks. The Giants had a good regular season last year, they just choked in the play-offs. This year has been shaping up like two years ago, get hot in the last few games, make the wild card, win the Super Bowl. As for Antonio Pierce, if there is no surgery involved, I don't see why he shouldn't be able to play at a similar ability. I wouldn't mind having him back.
The Giants have a nice core, they don't have to win it all this year. Their foundation is being set on offense and they'll still have other playmakers on D. The NFC East is loaded with a bunch of young talent. Pitt, SD, and even NE (all three are tough playoff opponents as well) can rebuild for the future easily if it doesn't work out. The NFL has a lot of parity.