Correlated same-game look: if the Pats hang around and cover +3, it's because this stays a low-scoring, ugly game, which pushes it Under 44.5 too.
Both offenses are unproven Week 1 units, and the two legs at -102/-112 combine to a fair +275 for buying that correlation instead of two separate bets.
A Pats special-teams or defensive score could cover the spread and spike the total in the same play, so this un-correlates fast in a chaotic opener — lean, not a lock.