PHILADELPHIA — For the second straight day, the Mets game against the Phillies was postponed due to rainy weather. With a steady shower and winds blowing at 19 mph at Citizens Bank Park, Saturday evening’s matchup was rescheduled as part of a single-admission doubleheader on Sunday. First pitch has been set at 12:35 p.m. with Game 2 beginning about 20-30 minutes after the final out of the first game. “We’re at their mercy, and rightfully so,” Buck Showalter said of the Phillies’ decision to postpone, which was announced just about two hours before the originally scheduled 4 p.m. first pitch on…