The 23-year-old, acquired from the Tigers on July 23 as part of the Anibal Sanchez-Omar Infante trade, got the nod to catch Josh Johnson. To share the moment, Brantly's parents, Robert and Yvonne, took a red-eye flight from Southern California to Miami. A couple of his cousins also made the trip from the West Coast, as did his agent, Mike Seal.
While Brantly's grandfather passed away a few years ago, his impact remains on the Miami catcher.
"I always hear his voice saying, 'Robbie, hit that ball with authority!'" Brantly said. "When I'm up there, and I get a good piece, I'm like, 'I hit it with authority.'"
The Marlins are certainly hopeful Brantly can make an impact with his bat. In 14 games with Triple-A New Orleans, the 23-year-old batted .365 with two home runs and 11 RBIs.
"Like any kid who loves baseball, this is like a dream come true," Brantly said. "I'm excited to get out there on the field and show them what I can do. Hopefully I can contribute and help this team."
All afternoon, Brantly received messages from family, friends and former teammates in the Tigers' organization. Among them was Nick Castellanos, Detroit's top prospect, who played at Archbishop McCarthy in Broward County.
Castellanos roomed with Brantly at Double-A. Some Castellanos family members attended Tuesday's game.
Miami manager Ozzie Guillen promises to give Brantly plenty of playing time. How much is still being figured out.
John Buck is a veteran and former All-Star who is a right-handed hitter with a track record. But it's been a rough year for Buck, who is hitting .184.
"I talked to Buck," Guillen said.
It was made clear that Brantly will play.
"On the other hand, I'm not going to leave John on the bench," Guillen said. "We're going to pick spots to play [Brantly]. We're going to try to get the kid to catch everyone in the rotation. But in the meanwhile, Buck also has to play games. He's not going to be like a backup. We'll figure out how we're going to do it. It's a little bit of a headache. I have to respect Buck, he's a veteran player. And I respect that."
The Marlins optioned Brett Hayes on Sunday to Triple-A New Orleans to make room for Brantly.
"You have to blame Buck, and you have to blame Hayes," Guillen said. "[When] Hayes was playing good, he was here. Buck is our guy, but we need two catchers. You're going to call up this kid, not to have him on the bench. He has to be playing.
"To be honest, Hayes, he was not doing what he was supposed to do. That's why we made this move."