Chris Hatcher, for instance, threw three innings against Colorado Springs in his latest relief stint at Triple-A New Orleans before he was brought up to the big leagues.
The purpose is to build each reliever up, and by working more than one inning they will be forced to pitch in more situations.
"Organizationally we talked about the development of our pitchers and our relievers," Marlins manager Mike Redmond said. "Really, if we're going to get these guys better, it's hard to get better throwing one inning. I think what we've tried to do is stretch these guys out and get them multiple innings."
If a reliever throws two or even three innings, he will get a couple of days off, and the next option will be used in a similar capacity.
Also, relievers at the developmental levels don't settle in assuming they have a set role. Hatcher, for instance, has closed at Triple-A. But on the Marlins, Steve Cishek is a proven closer. Hatcher's role will be middle-innings relief.
On Friday night, Hatcher threw two scoreless innings of relief with three strikeouts in Miami's 9-5 loss to Milwaukee.
"When they come to the big leagues, they're more prepared for 35 to 45 pitches and multiple innings at a time and give us more flexibility," Redmond said. "I think it's great for all our pitchers to get extended out, and that helps in their development, because let's face it, the more pitches you throw the better chance you're going to have to work on your pitches and the off-speed pitches.
"If you go out there [for] only one inning and a few pitches, there's probably not a whole lot of development there. I think that's kind of been the thinking."
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter