Evan Gattis went from non-roster spring training invitee to Braves cleanup hitter in under two months, and Tuesday night the rookie catcher provided another example of why his stock has spiked so quickly. Gattis hit a two-run homer in the first inning, and Kris Medlen and the bullpen held on for a 3-2 win against Miami at Marlins Park, pushing the Braves’ winning streak to five games and majors-best record to 7-1. “What else can you say about Evan Gattis?” Medlen said. “He was the difference in the game, for me.” Medlen (1-1) limited the Marlins to three hits and one unearned run in seven innings, with two walks and one strikeout. Miami scored in the second inning after Braves center fielder B.J. Upton dropped a fly ball that allowed Greg Dobbs to reach second base to start the inning. “I think the last three innings he didn’t even get to double digits in pitches,” Braves manager Fredi Gonzalez said of Medlen, who retired his last 10 batters and threw 24 pitches in his last three innings after throwing 66 in the first four. “They got an unearned run on a ball we dropped in the outfield, and that was pretty much it. He did a heck of a job. “I’m glad we were able to get him some runs and get him the win.” Andrelton added three hits for the Braves, who have their best eight-game start since they were 7-1 in 2007. After Justin Upton’s RBI double in the eighth pushed the lead to 3-1, the Marlins scored a run in the bottom of the eighth on Placido Polanco’s two-out single off left-hander Eric O’Flaherty. The Braves chose to intentionally walk Giancarlo Stanton with a runner at third and two out to put the potential tying run on base. O’Flaherty induced a Greg Dobbs groundout to avoid further damage after the Polanco hit. “(Stanton) is a guy that can hit the ball out of the ballpark,” Gonzalez said. “I didn’t like (walking Stanton), but you’ve got to pick your poison.”