Nothing brings people together like tragedy and triumph. Nothing can more quickly turn your out group into an in-group than a grand event. So, the chants of “U-S-A!” that broke out after the American triumph during Sunday’s Mets-Phillies game among the rivals mirrored the abundance of I      NY shirts that appeared nearly ten years ago as the Mets played another rival after September 11^th. The event need not be a national moment either. The year that both the Mets and Yankees made the World Series produced a camaraderie in New York City which seemed to surprise those who weren’t around to see it. Mets fans and Yankee fans became baseball fans. And the city that had been a Yankee town for the previous few years embraced its more general baseball identity.  A new in-group was formed and anyone who wasn’t a New York baseball fan, or all those people who wrote about how it was going to tear the city apart, became the new out group. At least until the games began…