[quote name=\'joker316\' post=\'229834\' date=\'Nov 4 2009, 08:02 AM\']Was "Phillies" a shortened name of Philadelphians (similar to the Mets being short for Metropolitans)? If so, then the form of the word rule applies and...buzz![/quote]
From Wikipedia: "After being founded in 1883 as the "Quakers", the team changed its name to the 'Philadelphias', after the convention of the times. This was soon shortened to 'Phillies'."
(In turn, cited from The Team-by-Team Encyclopedia of Major League Baseball)