Does a serious rivalry really exist between these two teams? Seems more likely that MLB, or perhaps simply writers of the press, are speculating this simply to create some baseball drama, which is perfectly fine in my opinion. I don't care if rivalries are media-generated or not; I appreciate the heightened tension no matter where it's coming from.
And, sure, the Phillies and Mets have their history. But if you asked Phillies fans today who our biggest rival was, would most people answer the Mets?