There’s optimism the Marlins may soon be getting some of their top starting pitchers back. In the meantime, the club is dealing with the reality that it is relying on some untested rookies.

Right-handed pitching prospect Humberto Mejía is one of them, and the 23-year-old had a respectable second big league start on Tuesday. But a couple of home runs hurt him, and the Marlins were unable to recover in an 8-3 loss to the Mets at Marlins Park.

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The Marlins (9-8) have now lost four straight games and are struggling to score runs. They’re also relying on starters with little to no previous big league experience.

“We know we're asking a lot,” Marlins manager Don Mattingly said. “You still get disappointed when you're hoping for the best in that scenario. But you have to be realistic at the end of the day. You don't have to be realistic at the beginning of the day, though. You can say, ‘This kid has got a chance to make pitches and show us what he can do.’ And I do think he is showing us that he has a chance to be a quality Major League pitcher.”

Mejía, who was recalled from Miami’s alternate training site in Jupiter, Fla., didn’t pitch higher than Class A Advanced Jupiter last year.

“It's a huge leap,” Mattingly said. “These circumstances that we've been going through are obviously different than any other time. So guys are getting opportunities. You probably don't get this opportunity in a regular-type season.”

But due to the fact three starters -- Sandy Alcantara, Caleb Smith and José Ureña -- are on the injured list, Miami’s starting pitching depth is being tested.

Mattingly praised the poise that Mejía displays on the mound despite being a rookie.

“This is a game in which I think you have to have composure,” Mejía said through an interpreter. “That can help me a lot. I know I need to learn a lot of new things and develop. If I can keep my composure, I can make better pitches and get what I want to do, which is get outs.”

The Marlins’ bullpen also is being taxed. Pat Venditte, who tossed 1 1/3 scoreless innings Tuesday, exited in the sixth with a right oblique strain. Six Miami relievers combined to allow five runs on six hits, with four walks and five strikeouts in five innings.

Mejía and left-hander Daniel Castano are two rookies currently in the rotation. Both made their Major League debuts this season. Jordan Yamamoto, who made 15 starts last year as a rookie, was optioned to the alternate training site on Monday after posting an 11.42 ERA in three starts this year.

The encouraging news is that Alcantara is scheduled to face hitters on Wednesday, and Smith and Ureña also are ramping back up. Until they are ready, rookies like Mejía are being asked to get their feet wet in the big leagues.

Both of Mejía’s starts have been against the Mets, with the other coming on Aug. 7 at Citi Field, where he threw 2 1/3 innings, giving up one run. He was optioned to the Jupiter site after that start to give the club another bullpen piece. The club’s intention was to bring him back to face the Mets on Tuesday.

“After New York, I went to Jupiter and I had an outing there,” Mejía said. “After that, I kept working and getting ready for this one. But I have to keep working on many other things.”

Added to the 40-man roster in the offseason, Mejía quietly has been one of the Marlins’ most intriguing pitching prospects. At two Class A levels in 2019, he compiled a 2.09 ERA while going 5-2.

On Tuesday, he kept the Marlins in the game through four innings but surrendered home runs to Brandon Nimmo in the third and J.D. Davis in the fourth. Both were no-doubt drives. According to Statcast, Nimmo’s blast was projected at 415 feet, and Davis’ at 418 feet.

“They came out attacking,” Mejía said. “It was something I was able to learn today.”

Amed Rosario added a homer for New York off Nick Vincent in the seventh inning.

The Marlins have used nine different starting pitchers this year. Even with the lack of continuity, the rotation’s ERA entering Tuesday was 4.03, which was 10th best in the Majors.

Now it’s a matter of if the rotation can hold it together until the established starters return from the injured list.

“We've just got to hang in there. That's the thing,” Mattingly said. “We want to be patient to a point. We have high expectations of what can happen on a nightly basis.”

Despite their longest losing streak of the season, the Marlins are one game behind the Braves (14-11) for first place in the National League East.

“We're not going to go away,” Mattingly said. “We're not going to quit trying to win games. We're not going to look at what we don't have. We're not going away, and I'm not going to try to manage differently. We're going to do the best we can with the guys we've got, and we're going to get it to where we want to go.”