NE schedule wasn't that bad - played 5 games vs playoff teams (Mia(2), Hou, Pitt & Sea) + 2 games against the two highest power ranked teams not to make playoffs (Den & Arz). Schedule started out above average and ended below as BUF-NYJ-CIN-BAL ended up worse than was expected early in the year.
NE -5 at home - in the games Brady played this year (home and away) NE winning margin: 20, 18, 11, 16, -7 SEA, 13, 5, 16, 7, 13, 38, 21 and 18. They were blown out by SEA and the only other game that was close vs. NYJ who were coming off a Bye.
NE laying -5.5 is a few points less than the power rankings - not a bad value at home for team off a weak performance who pretty much won every game by 7+ points.