Why did they lose?

They lost because

• Brady underthrew Gronkowski and got picked.
• Welker dropped a very catcheable ball that would have put them in field goal range and extended their last real drive.
• Belichick wasted a timeout on a no-chance challenge.

Yes, Gronkowski's limitations significantly hurt the offense. Yes, the defense didn't stop the last drive. Yes, the Giants came up with another miracle pass/catch, and yes, every ball that hit the ground bounced right into the hands of a Giant. But in the end, they lost because the the strengths of the team - the brilliant coach, the All World QB and the NFL's leading pass catcher - all made critical mistakes in the fourth quarter. The game was there to be won. They failed to win it.