June 15, 2004 THE WORST TRADE IN BASEBALL HISTORY By John StrubelIn Blog, MetsJune 15, 20048 Min ReadAdd Comment 15June Every year since 1977, New York Mets fans have viewed the Major League Baseball trade deadline as the darkest day in team history. The trade deadline – June 15, 1977 – was the day the Mets traded Tom Seaver.