MIAMI -- Sandy Alcantara, the Marlins’ promising 23-year-old, made his 13th start of the season Monday, and 19th of his big league career. It also was the hard-throwing right-hander’s first appearance against the organization that gave him his first professional opportunity.

The results were mixed for Alcantara, who flashed a power fastball that maxed out at 98.3 mph. But he also walked four, and was hurt by a critical error, in the Marlins’ 4-1 loss to the Cardinals at Marlins Park. Miami has dropped five straight.

• Box score

Standard statistics aside, what was disappointing to Marlins manager Don Mattingly was that it was another Alcantara start that the right-hander didn’t go on the attack.

“It's what we talk about with Sandy,” Mattingly said. “The days he comes out aggressive, on the attack -- his stuff -- he's a No. 1. Then you see a game like this, and you feel like, 'OK, we're not there yet.' You see a couple of good ones, and then you see this one. It's like, you don't quite know what he's thinking. Where did the aggression go?”

Alcantara was an international signee by the Cardinals in July of 2013, receiving a $125,000 bonus. He made his MLB debut for St. Louis in 2017, appearing in eight games in relief.

“Maybe it's one of those things we've got to keep talking about,” Mattingly said. “You just want him to understand how good his stuff is. If he would just go on the attack. His stuff is good, and he will play with anybody out there when he's on the attack. I don't care who he his facing. He's a handful."

Acquired from St. Louis as part of the Marcell Ozuna trade after the 2017 season, Alcantara is a fixture in the Miami rotation and a core part of what the organization is building. On Monday, the lanky righty had a tough time against the two-time All-Star outfielder.

“I was pretty excited to face my old team,” Alcantara said. “I tried to do my best, but today wasn't my day. In the first and third, I was a little lazy. After that, I said, ‘I have to be aggressive.’”

Ozuna had two hits and a walk off Alcantara, and scored twice.

In the fourth inning, Ozuna doubled and scored the first run on Yairo Munoz’s two-out double. And in the sixth inning, Alcantara surrendered three runs, none of them earned, because catcher Jorge Alfaro made a throwing error on Kolten Wong’s sacrifice bunt. After the throw sailed down the right-field line, two Cardinals scored -- Paul Goldschmidt (who singled) and Ozuna (who walked).

“I just tried to get an out for him,” Alfaro said. “I just threw it away. But, I think [Alcantara] did a really good job.”

That marked the end of the night for Alcantara, who allowed four runs (one earned) in five-plus innings. He struck out six.

Alcantara didn’t receive much run support. Michael Wacha threw six shutout innings, and benefited from three double-play grounders.

Harold Ramirez had three hits for the Marlins, including a double in the seventh inning. He scored on Alfaro’s RBI groundout.

“Quite honestly, it was a really disappointing game,” Mattingly said. “It doesn’t look terrible because it’s a 4-1 game. It looks like maybe it was a game, or whatever. But I was really disappointed with the energy.”

Mattingly also didn’t use Sunday’s 7-6 loss in 12 innings as an excuse.

“If it is, that’s disappointing, too,” Mattingly said. “You’ve got to get ready to play.”