"It's moving in a positive direction," manager Dan Jennings said. "It's good for Carter, and certainly good for us, as well."
Capps likely would pitch in at least one rehab-assignment game. Barring any setbacks, he could be back with Miami by Wednesday or Thursday.
"These steps and rehabs for all these guys are tests," Jennings said. "If they get to the next progression and it feels right, then, yes, there is a good chance you can see him in the next series."
Getting Capps back would bolster a taxed bullpen.
Capps, armed with his 100-mph fastball, has been one of the dominant right-handers relievers in the game this season. In 31 innings, he has a 1.16 ERA and 58 strikeouts. His WHIP is a minuscule 0.81.
It's been a breakout season for Capps, who is among the hardest throwers in the game. According to the Baseball Savant web site, Capps has thrown fastballs of 100 mph or higher 10 times. That's the sixth most of any pitcher in the Majors.
Cincinnati's Aroldis Chapman tops the list with an astounding total of 227, and Kansas City's Kelvin Herrera follows at 47. Pittsburgh's Arquimedes Caminero is next at 37. Detroit's Bruce Rondon is at 22, and Nathan Eovaldi, the only starter on the list, is fifth with 16.
Along with Capps, the Marlins are confident some other injured pitchers are close to returning. Jarred Cosart (vertigo) is scheduled to make a Gulf Coast League start in Jupiter, Fla., on Saturday morning.
Cosart is on the Minor League disabled list, but he could be joining the big league rotation by early September.
"Right now, everything has been great," Jennings said. "No signs of the vertigo. He's just got to build up his pitch count. Once he gets to a certain level, he should be back and ready."