The NFL is trying something different this year. They are playing a regular season game on October 28th in London: the Giants versus the Dolphins. Technically it is a Dolphins home game. In reality, there should be no home field advantage for either team. The Dolphins basically have 7 home games, 8 road games and 1 neutral game. If home field is worth about 8%, then the Dolphins have lost about 0.08 expected wins. On the other hand, the Giants benefit and gain that 0.08 expected wins.
Both teams have byes after the game in London, so I would not anticipate this long trip will hurt either team for the remainder of the season.
Here is an article from the Miami Herald about the London home game forthe Dolphins:
http://www.miamiherald.com/sports/football/story/147058.html
Make sure to make this adjustment in your futures and regular-season win calculations. Those wagers will show up soon in Las Vegas especially with pre-season games starting in about a month.