Even though it was nothing more than a spring training game, don’t think John Maine wasn’t excited. Maine, a former rotation mainstay for the New York Mets who hasn’t pitched since 2010 because of an assortment of injuries, completed his two-inning allotment for the Marlins as their starter in Saturday’s Grapefruit League opener, an 8-3 victory against St. Louis. “It’s been [three] years,” Maine said. “I was really antsy, really excited.” Maine said his first spring outings have not usually turned out well in the past, which is why he was especially pleased with Saturday’s performance, one in which he gave up only one hit — a wind-aided solo homer by the Cardinals’ David Freese. “It’s the first time I think I’ve ever gotten through two innings in my first start,” Maine said. Maine, a nonroster invitee, is among several pitchers contending for the open fifth spot in the rotation.