Marisnick, a 22-year old outfielder, hit his first major league home run to help lift the Marlins to a 3-2 victory over the New York Mets on Wednesday night.
"It felt good," Marisnick said. "It was the first at-bat where I really slowed everything down."
Miami starter Henderson Alvarez (2-1) pitched into the eighth inning. He allowed two runs and six hits in 7 1/3 innings, and had two hits and scored a run, too.
"I felt I prepared well, and all of my pitches were working good tonight," Alvarez said.
Alvarez is 2-0 with a 1.33 ERA in his last four starts.
Marisnick and Alvarez were acquired from Toronto, along with shortstop Adeiny Hechavarria, in November's blockbuster trade that sent veterans Jose Reyes, Mark Buehrle, Josh Johnson, John Buck, and Emilio Bonifacio to the Blue Jays.
"I think you realize how good of players we got in that trade and how much those guys are going to be a big part of not only this team this year, but the future," Marlins manager Mike Redmond said. "These guys can play."
Dunn issued a leadoff single to Buck before retiring the next three batters to end the game.
"That was his inning," Redmond said. "We want him to go out there and not have a guy warming up in the bullpen behind him and let him take that inning and see what he could do.
"He did a great job."
Marisnick homered off of Jenrry Mejia (1-1) in the second inning to give the Marlins a 1-0 lead. He was hitting .179 (5 for 28) in his first eight games before the home run.
"It was honestly the farthest thing from my mind," said Marisnick, who initially received the customary silent treatment from his teammates in the dugout after the home run.
Mejia gave up three runs in six innings.
Eric Young nearly matched Marisnick's homer in the third inning, but his long drive to center field hit the top of the fence and stayed in play. Umpires used video replay and upheld the original call, giving Young a triple.
He was stranded at third base.
"I thought it came off the wall funny," Mets manager Terry Collins said. "That's why I went out. (Second base umpire) Andy Fletcher said, 'I know it came off the wall funny. We'll take a look at it.'"
Redmond had no complaints about the call.
"I think they got it right," he said.
The Marlins added to their lead in the bottom half of the third inning with back-to-back sacrifice flies by Polanco and Stanton that made it 3-0.
New York broke through against Alvarez with an RBI double by Ike Davis in the sixth. It was the first run allowed by Alvarez in 18 innings, the longest streak by a Marlins pitcher this season.
Young led off the eighth with a walk and advanced to third on a ground ball to Polanco at third. Alvarez was relieved by Chad Qualls, and Young scored on a passed ball to pull the Mets within 3-2.
"I was just playing the percentages, who was at third base and who was at first base," Young said of his alert baserunning. "I felt good about going."
Carlos Torres, New York's scheduled starter for Saturday, pitched a scoreless eighth inning. ... A video montage of Qualls' celebration stumble from Tuesday's game was shown on the scoreboard hours before the game as the Marlins continued to laugh at their teammate's expense. "We lost a tough game, but we all laughed about the whole situation," Redmond said. "That was great. Classic." ... Before the game Redmond praised Hechavarria for being the best defensive shortstop in the National League. "I've not seen a better shortstop in this league than Hetch, and hopefully he'll get the notoriety he deserves," Redmond said. ... RHP Matt Harvey (8-2, 2.11 ERA) will start the series finale for the Mets on Thursday against Marlins RHP Tom Koehler (2-6, 4.67 ERA).