"Very intriguing. He's got great stuff," manager Mike Redmond said. "He's got a great arm. He's an exciting type of guy."
Heaney is scheduled to throw one inning in a "B" game against the Cardinals on a back field on Wednesday, and he may be squeezed into a Grapefruit League game later in the week. The team wants to see him against MLB hitters.
As of now, he isn't scheduled to make any Grapefruit League starts, but that is subject to change.
The Marlins are in no hurry to rush the 22-year-old. He is regarded as a long shot to make the Opening Day rotation, but performance could change those plans.
The Marlins aren't hesitant when it comes to promoting their prospects. A year ago, Jose Fernandez made the leap from Class A ball to the big leagues, and went on to be the National League Rookie of the Year.
"When you think about Jose and what he was able to do last year," Redmond said, "Heaney is one of those guys who is exciting. He's a big part of our future. When that future starts, who knows? We know he's a big part of it."
The ninth overall pick in the 2012 First-Year Player Draft, Heaney has college experience having pitched at Oklahoma State. He dominated at the Class A and Double-A levels last year, combining for a 9-3 record with a 1.60 ERA.
What Fernandez did last year raised the bar for pitching prospects. But that doesn't mean the Marlins are looking to speed the development of Heaney.
"Last year was a different set of circumstances," Redmond said. "We got in a situation where we had some guys get injured. We needed someone, and he was the best guy. It really became an easy decision. He was the guy we needed to take, so we did."
The Marlins have pitching depth, and several candidates are in line for the fourth and fifth spots.
Jacob Turner, Tom Koehler, Brad Hand and Brian Flynn are also in the mix for the fourth and fifth spots.
"We have more depth," Redmond said. "We don't feel like we have to push [Heaney]. At the same time, too, we want to see what he can do, and try to give him as many opportunities as we can."