I believe this team still has:
1) some quickly aging linebackers (Bruschi lost a step last year and Vrabel can't be far behind,
2) a secondary that seems to take injuries every year (Harrison, Wilson, Gay),
3) a starting cornerback who may or may not even be with the team (at least for the first 10 weeks)
4) an unproven full-season running back (Maroney split carries in college and didn't play the whole year last year),
and 5) injuries are always a concern for every team (Brady has NEVER been injured, and what if Thomas suffers a freakish 2nd-game-of-the-year Colvin-type injury).
The additions made in free agency have been great. Awesome, really. Taking a 4th round flyer on Randy Moss is just the icing on the cake.
But no team is perfect. And the most talent "stacked" teams don't always win (last year, the Chargers had more "talent" than the Patriots, the Rams had more talent than the Pats in 2001, and the 2006 Colts weren't as talented as the 2005 version).
This team is a favorite to win it all (along with the Colts and Chargers).
But undefeated? The fact that no one has managed a 16-0 regular season, much less a 19-0 complete season, tells me that it's ridiculous to even discuss this possibility.
Worst, it's ****y. And bad karma.
Enjoy what the Pats have put together. 2007 looks to be a heckuva year (against a heckuva schedule).