Martinez was so much a fan of the Marlins that while in high school, he was assigned a current events project and decked out his display board in anything he could find related to the Marlins. The only problem was the fall assignment was late and his parents wouldn't let him attend a game in the 2003 World Series because he hadn't finished his homework.
"They said, 'You've got to finish your project. It's worth 50 percent of the grade,' " he said. "I had to stay home and watch it, and they went and left me. I would sit there in front of the TV and yell and go crazy and do my project at the same time."
The Martinez family, led by his Cuban-American parents, Mayra and Julio, and countless other friends and relatives will be in the stands this weekend at brand new Marlins Park to watch their son, J.D., make his return to Miami as the starting left fielder for the Astros. For at least three days anyway, the Martinez clan won't be rooting for the now-Miami Marlins.
Martinez, 24, is one of the Astros' rising young stars, having burst onto the scene last year. He was called up from Double-A Corpus Christi following the trade of Hunter Pence in late July and set an Astros rookie record for RBIs in a month with 28 in August.
The Astros drafted Martinez in the 20th round in 2009 out of Nova Southeastern University in Davie, Fla., and he shot through the Minor League system with gaudy offensive numbers.
Martinez is the only Astros player to have hit safely in all six games this season, and he enters Friday's series opener with a .364 batting average with two homers and six RBIs.
"It's exciting," he said. "I get to go back home and play in front of my friends and family and people that never really have gotten to see me play at the professional level. Everyone is really excited, and I'm really excited to go. I know I'm going to be really, really nervous, because if I do bad, or if I do something stupid, they're going to get all over me. I'm going to hear about it everywhere I go because I'm home."
Martinez, who has five sisters, has had a flood of emails and text messages in recent days from people who want tickets or simply want a chance to say hello to Martinez while the Astros are in Miami.
This could be the Astros' final trip to Miami for quite some time, considering they're moving to the American League next year. That makes it only more special for Martinez.
"It's cool because we used to all go to the games together, and now they get to come and see me," he said.
The only thing that might have made the trip even better is if the Marlins were still playing in Sun Life Stadium, where Martinez developed so many memories attending games growing up. The Astros and Marlins on Friday will be playing the second official game at Marlins Park, the team's new 37,000-seat retractable-roof stadium on the site of the old Orange Bowl.
And who knows? No one has yet to hit an official homer in the ballpark, so Martinez could make some history.
"I wanted to play in [Sun Life Stadium] because that's where I used to watch the games all the time, and I always wondered what it would be like to be on that field and play a game there," he said. "This stadium is brand new, so you couldn't ask for anything better, really."
Martinez believes the new stadium -- and its roof -- is exactly what the Miami needs to embrace baseball.
"You could never go to a Marlins game back then and go hang out afterwards," he said. "You go to a Marlins game and sweat and go home and take a shower. I think it's going to have more of that Miami Heat style now. People will go to the game and go to South Beach afterwards. I think that's very good for the city, because it's the new, hip thing. A lot of people are going to be into it."
The first order of business for Martinez's homecoming, however, is trying to get the Astros back on track after a pair of losses to the Braves on Tuesday and Wednesday. But that doesn't mean Martinez won't be able to enjoy being home for a few days.
"There's no place like home, they say," he said. "I've been to a lot of cities and a lot of cities are nice. I just could never see myself living somewhere else. That's all I really know. You get a sense of relaxation when you're home."