The fact that Halo only had 75% is more evidence that bracket makers aren't totally looking at seeds. Halo/Master Chief always get crazy prediction percentages.
I doubt PW breaks 60%.
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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