It's a mile+ walk to the stadium. No shuttles. It's also across the street from Gillette. Getting across Rt.1 is limited. You have to wait a long time for police to stop traffic. Also that lot is impossible to go north on Rt.1 when leaving. You have to go south. There's only two ways out of that stadium zone: north or south on Rt. 1.
If you want to head north after the game, instead of parking in the Backers lot, park across the street in a place called Foxboro Terminals, then cross the street at the light at Water St. and hang out with the backers. Cross back and walk to the stadium that way. After the game you will have a much easier time getting on 95 north because you'll be parked on the side of northbound traffic.
Bostin Bills Backers Tailgate