WHEN ISABELLE DE LEON and Michael Volpe drive to and from work in Manhattan, New York, each day, turning on sports talk radio is automatic: WFAN's Boomer Esiason in the morning, ESPN New York's Michael Kay on the way home. When the couple met at SUNY Downstate Medical School in Brooklyn in 1990, they bonded over their New York Yankees fandom, trading trivia questions and going on dates in the bleachers. They were the couple who would sleep outside Yankee Stadium when playoff tickets went on sale. And when Isabelle went into labor on April 27, 2001, the couple watched the Yankees beat the Oakland Athletics on television at Mount Sinai Hospital before she gave birth to their son the next morning.