1. The sell out streak each team has going is impressive in its own right but the Sox streak is inflated because they sell a ton of their unused seats to Ace Ticket and count them as sold.
2. I've had Sox season tickets for 15 years now and trust me, from 97-03 you could have a whole row to yourself in the right field grandstand before school got out or after the kids were back in school. Three of those years the Sox were in the playoffs and they were not below 500 in any of them. Those are the equivalent of the 2002 Patriots teams when Gillette was still banged out.
4. Gillette may not look packed but every seat is sold and 99% of the people are there. One BIG advantage Gillette has over Fenway is the concession stands are on the outside wall of the stadium allowing for fans to stand along the concourse and watch the game. There are great standing room areas all around the stadium. At Fenway you do not have that luxury. If you want to see the game action live, not on a tv, you have to stay in your seat.
5. Steeler fans travel very, VERY well. Seeing terrible towels in Foxboro is no different than hearing "Let's go Red Sox" in New York or Philly when Boston is in town. Close opponent, good opponent, easy drive.
6. I think the NY Times/Globe recently sold their stake in the Red Sox, though I could be wrong.