A.J. Pierzynski is 38 and was signed by the Braves in large part to serve as a mentor to rookie catcher Christian Bethancourt, to show him the ropes and help other veterans shape the attitude and confidence of a team with impressionable youths.

But Pierzynski was signed also because he can still hit.

The Marlins can attest to that after Wednesday night, when the big catcher hit a two-run homer in the seventh inning to lift the Braves to a 2-0 win and complete a three-game series sweep at Marlins Park, the first season-opening sweep for the Braves since a three-gamer at Philadelphia in 2007.

“For my first hit to be a home run as a Brave is pretty cool,” said Pierzynski, who homered in the third plate appearance of his Braves debut, after Bethancourt caught the first two wins. “But more important is the way we pitched tonight. Our guys were lights-out from Shelby (Miller) all the way to (Jason) Grilli, that was the biggest thing.

“I was so proud of the way we pitched, not only tonight but the whole series. I thought we did a really good job containing them, making big pitches in big situations.”

After starter Miller labored through five innings in his Braves debut, rookie reliever Brandon Cunniff (1-0) got the win in his second major league appearance, retiring all five batter he faced after entering the game to start the sixth inning.

Left-hander Luis Avilan got the third out of the seventh inning, Jim Johnson gave up one hit and struck out two in the eighth, and Grilli pitched a perfect ninth with one strikeout and two groundouts for his second save in as many opportunities since taking over the closer role after Craig Kimbrel was traded Sunday.

After the game, Braves manager Fredi Gonzalez walked into the clubhouse and handed the lineup cards to Cunniff and said, “Nice job.”

“We played good baseball,” Gonzalez said. “We pitched, got timely hitting. Today A.J. hits the two-run homer, that’s the thing everybody’s going to talk about. But he did a nice job navigating three or four pitchers through that lineup. And that’s what he’s capable of doing. Veteran of 15, 16 years in the big leagues, and he knows how to do it.”

It was an encouraging start for a Braves team that many pundits have picked to finish with a worse record than the Marlins and just about everyone else in the National League. The Braves became the first team in the majors with a 3-0 record.

“Every series is important, but there’s so much emphasis put on the first one,” Pierzynski said. “To come in here and play against a team that people are expecting really big things out of, and to play the way we did, hopefully carries over. But it’s only three games. There’s a whole lot more games. Hopefully it will continue to go like this and we’ll continue to stay positive. If we pitch like this, we’ll be fine.”

Pierzynski homered in his season debut and third plate appearance against Marlins right-hander Tom Koehler, after Bethancourt caught the first two games. The Braves had only three hits through six innings against Koehler, who has had five consecutive quality starts against Atlanta over two seasons without a win.

After being teammates with Pierzynski last season in St. Louis, Miller wasn’t at all surprised to see him hit a game-winning homer.

“Oh, no, he’s got power for sure. He’s a big boy,” Miller said. “You expect him to make those kind of plays in those kind of situations when we needed some runs. He did a good job, put a good swing on that ball and got us our two runs to win the ballgame. The bullpen came in and did a good job. A.J. did a good job behind the plate as well.”

Miller allowed four hits and two walks with four strikeouts while running up a high pitch count (97, including 61 strikes). He said he needed to be more efficient and get deeper in games, but praised the bullpen and the timely hits the Braves got throughout the series.

The Braves got Miller from the Cardinals in the November trade that sent Jason Heyward to St. Louis. That was the first in a series of big Braves trades that continued unabated through this week, when Kimbrel was dealt to the Padres on the eve of opening day. In the first series, at least, the Braves bullpen didn’t miss a beat.

“We’ve got two pretty good guys at the back end who’ve done pretty special things in their careers,” Pierzynski said. “Jim Johnson, having faced him, I always ask him how the heck do you ever give up a hit. His stuff is that good. And Grilli is just such a competitor. I’ve known Grilli for almost 20 years. Those guys are pretty good at the back end.

“And we have the ability, because of some of the arms that we have, to mix and match some of the other guys. And they’ve done a great job. Some of these young kids have come in and thrown strikes, which is the biggest thing. If they continue to do that, then we think we can have some success.”

If this opening series was any indication, Braves fans can breathe at least a little easier, while prognosticators who suggested that Atlanta would lose 90 or even 100 games might need to reassess.