Heaney on Sunday made his third start at Triple-A New Orleans, and he was tested. In a win at Colorado Springs, the former Oklahoma State standout gave up six runs (five earned) on 11 hits in six innings. He struck out four and walked one in the win.
Since getting called up from Double-A Jacksonville to New Orleans, Heaney is 2-0 with a 3.18 ERA with 18 strikeouts and one walk in 17 innings.
The Marlins are closely monitoring Heaney and, at least publicly, are non-committal about his arrival date.
"Obviously, he's at Triple-A," president of baseball operations Michael Hill said. "We know he's there."
Heaney, who turns 23 on Thursday, was the ninth overall pick in the 2012 First-Year Player Draft.
Because he threw on Sunday, he won't make his next start until Friday, and it will likely be at New Orleans again.
Not just the Marlins, but most MLB teams are factoring the Super 2 service-time date into their callup decisions. There is no firm day, because it is based on percentages from players across the league in a similar service-time situation.
But it appears Heaney could be in line to arrive around or shortly after June 11.
"I think the goal was always to just give him experience and give him more seasoning," Hill said. "Obviously, he missed a little bit of the season last year and started off a little bit behind."
Heaney missed some time early in 2013 with a lat injury.
"We're just trying to give him experience, and he's handling each challenge very well," Hill said. "We'll continue to evaluate each start and see what's going on here at the Major League level."
The Marlins on Sunday promoted catcher J.T. Realmuto from Jacksonville after putting Jarrod Saltalamacchia on the seven-day concussion disabled list.
Realmuto caught Heaney at Double-A earlier in the season, as well as last year.
"As far as last year to this year, he's got a lot more control of his offspeed pitches," Realmuto said. "He's always had a plus-slider. His changeup has gotten tremendously better this year. He's been able to control it better. We almost went two or three starts without using his slider much. That's how good his changeup got."