For the umpteenth time in the last umpteen days, Mets manager Terry Collins opened his Wednesday afternoon at the ballpark with a barrage of questions about the playoffs. “We are not talking about the postseason again,” Collins said, all but throwing his palms to the sky before his team went out and lost, 6-0 to the Marlins at Citi Field to shrink their National League East lead to 7 1/2 games.