LOS ANGELES — The Miami Marlins, five outs from clinching a win of their road series against the powerhouse Los Angeles Dodgers and having a chance to sweep the National League West’s runaway leaders on Saturday night, saw new closer David Robertson implode, allowing three runs as the Dodgers rallied for a 3-1 win. The key hit was Mookie Betts’ two-run single in the opening game of a split-doubleheader. The NL West-leading Dodgers bounced back nicely from an 11-3 loss on Friday night, improving to 16-2 in August.