Marcus Semien hit a three-run homer, rookie Zac Thornton pitched five scoreless innings and the New York Mets matched a season high with their fourth straight win by beating the Pittsburgh Pirates 6-4 on Friday night. Semien’s second homer in two games and 14th of the season, a drive to left-center off Carmen Mlodzinski, capped a four-run third that put the Mets ahead 5-0. New York, last in the NL East, swept a three-game series in Cleveland before busing to Pittsburgh on Thursday night.