By Tim Molloy NEW YORK (TheWrap.com) – “It’s Always Sunny in Philadelphia” has always been good at playing the underdog – or even the dead dog, like the one that once fell out of a coffin during a baby funeral on the show. It takes pride in being mangy and scraggly and not up for a game of fetch. Creator and star Rob McElhenney’s anti-sitcom is driven by disgust at the phoniness of less funny, more popular shows. With near-total creative freedom, the series has become one of FX’s biggest hits. …