Garcia, 25, is on an innings limit this year, and to stay within a range of about 100-120, the left-hander is currently in the bullpen.
"It's either that or the Minor Leagues," Marlins manager Don Mattingly said on Sunday morning. "It keeps him competing at this level and he stays in somewhat of a routine.
"Obviously, the plan was to get him back into the rotation but also keep innings off him. It's probably not ideal, but for a young guy, opportunities aren't always like you get 650 at-bats. You get sections of time and you've got to show what you can do."
Garcia is at 45 frames after throwing two innings of relief on Saturday in an 8-1 loss to the Braves at SunTrust Park. The outing was a rough one, as Garcia gave up four runs and two homers.
It was his first game action since May 12, when he made a six-inning start against Atlanta in Miami.
"It's part of being a professional," Garcia said of staying sharp while being used less. "You've got to go out there and stay sharp and be ready for any situation you get called in."
The long ball has plagued Garcia all season -- either starting or relieving -- as he has surrendered 10. He was taken deep by Kurt Suzuki in the seventh inning and Freddie Freeman in the eighth in Garcia's 42-pitch outing.
Mattingly said Garcia shook off a number of pitches in his two innings, a sign that he wasn't comfortable with how he felt his stuff was playing.
"Pitch selection from him, there was a lot of shaking from him, which means he's going away from our game plan for really no reason," Mattingly said. "It's for whatever he's feeling, and that's really not a good sign."
Garcia has made nine appearances (six starts).
"I've got to think less," Garcia said. "I've been overthinking and it's kind of gotten in the way. It's just going out there and throwing and get out of my own way. Start thinking less and doing what I do and making the right pitches."
Worth noting • Rookie Brian Anderson is making right field look easy, as the 25-year-old has recorded three outfield assists. The arm strength of Anderson is something that the club feels will get opposing clubs thinking about trying to take extra bases.
"We expected him to be able to play it and keep his bat in the lineup, but he's been a force out there with his throwing," Mattingly said. "He's got a cannon. He's becoming a weapon out there in right field with his arm."
• Adam Conley isn't on any innings restrictions, and the left-hander for now is being used in relief after he has been mainly a starter throughout his big league career.
"Again, would you rather be starting in Triple-A or being in the bullpen in the big leagues?" Mattingly said. "We have a number of starters, and Adam could be one of them in the future. But, there's also going to be roles in that bullpen, and they're big league roles. A lot of guys have gone from starters to the bullpen and ended up being really good out of that bullpen. The bullpen, arguably now, is probably just as important as your starters. It's not like a bad job, it's a different job."