Offense had a bad first half in Washington, and only pulled away after the 'skins defense began to tire. It was 12-7 at the half, for crying out loud.
Against the Giants, the first score was off a blocked punt, and the second score came on a drive that started from the Giants' 20 yard line following an interception. The Patriots then had one legitimate scoring drive to end the half. In the second half, the Patriots scoring opened with a KVN TD on a forced fumble and recovery. So the Patriots only had 2 real scoring drives all game, against a terrible Giants defense.
So claiming that the offense had a bad day in Buffalo, but has been just ducky otherwise, simply doesn't fit the facts.