Actually, being the "Master of Soresu" had very little to do with the win. Obi-Wan goaded him and Anakin fell for it, literally. He did exactly what Obi-Wan expected him to do and Obi-Wan capitalized. It came down to which one was able to keep their head in the game.
I always felt that Obi-Wan was using Dun Möch there...or maybe inverse Dun Möch sense he pretty much begged Anakin not to try anything while he held the higher ground.