Garrett Cooper and Jean Segura homered, newly acquired relievers Jorge López and David Robertson played key roles and the Miami Marlins beat the Detroit Tigers 8-6 on Sunday. López (5-2) got the last two outs in the seventh and Robertson closed with a perfect ninth in his Marlins debut for his 16th save. “I’m trying to continue doing what I’ve been doing all season long,” said Robertson, acquired from the New York Mets late Thursday.