I'm not sure if he replaced anyone or not. Prior to his promotion I don't think they had a VP of Games Marketing. He'll still be reporting to Chris Capossela who is the Chief Marketing Officer for Microsoft.
I'm guessing the promotion is to indicate his increased importance in the company's organization due to the massive increase in the size of Microsoft's gaming division. Under him will likely be marketing heads for Activision-Blizzard, Bethesda, and one for the rest of the MS gaming studios (basically what he was prior to all the acquisitions).
Regards,
SB