Unfortunately, the MBTA will not be running a special train to Gillette Stadium for the show. Alternatively, my group of 4 has joined a charter bus trip on skedaddle.com. There are 5 people on the bus now, and we have to have 10 for it to go live. Those next 5 spots are $30/person. We'll leave from Biddy Early's pub in Boston at 4pm on Sunday, and the bus will bring us back after the show. You can reserve without your card being charged (it will charge you 48 hours before the ride if there is 10 or more people signed up), and can cancel up to 48 hours before event. I've looked at similar charter bus options, and this is by far the cheapest.
The link for the ride is letskedaddle.com/events/8566
Let's help each other out!