The 55-year-old actor was at Petco Park on Sunday afternoon to watch the Marlins beat the Padres, 6-3.
Wearing the new Marlins hat and an old team jersey, Bauer mingled with the players and manager Ozzie Guillen in the clubhouse after the game.
"Big Marlins fan," Bauer said. "I'm from Miami. I'm a Miamian. I actually saw the Miami Marlins Minor League team play in the old park."
The club the actor is referring to is the old Miami Marlins that previously was a Baltimore Orioles affiliate. They played at Miami Stadium, a prominent Minor League and Spring Training facility.
"I went there when I was 10-12 years old," said Bauer, who also attended the University of Miami.
When in Miami, Bauer offers his support for the club. He attended the groundbreaking ceremony at Marlins Park three years ago.
And last year, he threw out a ceremonial first pitch, along with Christian Slater, at Sun Life Stadium. That's where he received his personalized No. 17 Bauer jersey.
Manager Ozzie Guillen gave Bauer his new-look Marlins jacket on Sunday.
The actor, who makes Los Angeles his home, recently returned from New York City, where he was filming the movie "Last I Heard." When he realized the Marlins were in San Diego, he decided to drive down.
"I even brought my dog," Bauer said. "I didn't want to leave my dog at home. We came for the afternoon."
Bauer has already attended a Marlins game at Marlins Park, going during the Astros series in early April.
"It's the greatest park in the world," the actor said. "It's the most amazing place I've seen a sporting event. The most amazing place. Staples Center is pretty good for Lakers games. The Miami Arena [American Airlines Arena] is pretty good. But [Marlins Park] is so aesthetically beautiful. It's so fan-friendly, you can't help but have a great experience. Even if you're losing."
Bauer senses the Marlins are on an upswing after they've won six straight.
"This team had a few bumps starting off, but they're starting to jell. You can feel it on this West Coast trip," he said. "Now, if we can get back to the East Coast and start taking some games."