While the 1 seed may have kept some undecided people from choosing Starcraft, I don't feel that seeding makes that big of a deal. Had Halo got the 16 seed I expect Halo to be easily the bracket favourite.
Besides Phoenix doesn't exactly bring in the brackets. In 2008 he had 53% taking him 1st or 2nd among Bowser/Geno/Deckard. The 1 seed will give some extra points, but he's not turning anything large around.
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BOP Results: http://www.freewebs.com/charmander6000/Rivalry%20BOP.xls
BOP Topic: http://www.gamefaqs.com/boards/8-gamefaqs-contests/60566352