Back in mid-May, it was easy to envision Subway Series fireworks over the Fourth of July weekend. The Yankees had just taken two of three from the Mets in a hard-fought series in the Bronx, and both teams exited with leads in their respective divisions. “That’s a great team over there,” Mets first baseman Pete Alonso said after the May 18 series finale, which the Yankees won, 8-2. “That’s the …