Although the outcome of the night didn't go in his favor, Heaney showed tremendous potential in the Marlins' 1-0 loss to the Mets.
The downside was New York's Zack Wheeler went the distance for the first time in his career, tossing a three-hit shutout.
"I had no expectations coming into it, to be honest," Heaney said. "I just wanted to pitch well. I felt like early on I didn't know how it would go. I was on the edge with every guy. From that fourth inning, I got in a little bit of rhythm and got us six."
Heaney worked six innings, allowing a home run to David Wright in the first that proved to be the difference.
Still, the lefty become the sixth pitcher in Marlins history to throw six or more innings while allowing one or no runs in his MLB debut. Chuck Smith (June 13, 2000, at Philadelphia), Brad Penny (April 7, 2000, vs. Colorado), Adalberto Mendez (Sept. 6, 2010, at Philadelphia), Brad Hand (June 7, 2011, vs. Atlanta) and Josh Beckett (Sept. 4, 2001, vs. Cubs) were the others.
Heaney's effort impressed Wheeler.
"I was sitting on the bench just watching him, knowing that I was there not too long ago and knowing how it felt," Wheeler said. "He has a good arm and he's gonna do well."
Heaney's wife and parents were at the game.
"It was good," Heaney said. "I actually didn't see [my parents] -- just me and my wife up until she dropped me off at the field. My family did a good job of doing their own thing. They knew to give me space. I was already nervous enough without having to make sure everybody's getting settled and has a way to the field and all that stuff. It was good and just got to take some pictures on the field, so it's a special moment. I got to have a lot of family here, so it's really exciting."
The Marlins have a history of bringing up talented young pitchers. In many cases, the young prospects didn't disappoint in their big league debuts.
A year ago, Jose Fernandez was a 20-year-old making his first start on April 7 at Citi Field against the Mets. In five innings, the hard-throwing right-hander struck out eight and allowed one run on three hits in a no-decision.
One of the most celebrated debuts in club history was turned in by Beckett in 2001. The righty fanned five in six scoreless innings, allowing one hit in a win over the Cubs.
In 2003, Dontrelle Willis struck out seven in six innings in a no-decision against the Rockies.
Josh Johnson made his initial big league start on Sept. 30, 2005, and he fanned seven in 5 1/3 innings in a no-decision against the Braves.
On June 25, 2005, lefty Scott Olsen gave up two runs (one earned) and fanned seven in 5 2/3 innings in a win vs. the Rays in St. Petersburg.
A.J. Burnett made his Marlins debut on Aug. 17, 1999, and in 5 2/3 innings, he allowed one run in a victory over the Dodgers.
Anibal Sanchez broke on the big league scene in the second game of a doubleheader at Yankee Stadium. Sanchez got the callup on June 25, 2006, the day after the Marlins were rained out. In 5 2/3 innings vs. the Yankees, Sanchez didn't allow a run and collected the victory.
Penny logged seven innings, allowing one run, in beating the Rockies in his 2000 debut.