MIAMI — For six innings on Monday, Trevor Rogers looked the best he has all season for the Miami Marlins. But Miami couldn’t back his outing, dropping the first game of a split doubleheader against the Texas Rangers, 3-2. The Marlins are now 57-83 on the season, including 22-33 in one-run games. The Rangers (61-79) took the lead in the top of the eighth when Steven Okert allowed four consecutive batters to reach base with two outs, as Mark Mathias’ bases-loaded walk brought Corey Seager home. Monday’s loss stained Rogers’ impressive performance. It marked his third start since coming off the i…