WEST PALM BEACH, Fla. -- Rotation candidates Daniel Castano and Nick Neidert began the audition process during Miami's 6-1 win over Houston in seven innings in Sunday afternoon's Grapefruit League opener at The Ballpark of the Palm Beaches.

Castano, who utilized his sinker, slider and changeup, allowed one run on three hits with one walk and one strikeout over two innings. After being given a 4-0 lead in the first, he couldn't produce a shutdown frame. The lefty induced a double play, then allowed a double and an RBI single sandwiched around a walk. But Castano struck out Abraham Toro to strand men at the corners in a 32-pitch first. In the second, he worked a 1-2-3 inning on seven pitches.

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"It was just kind of like a good mental reminder of, 'Man, you don't need to make this thing so hard,'" Castano said on Zoom. "I was shaking off [catcher Chad Wallach] a little bit too much and just really going back out there and trusting myself, which was what I did last year."

The 26-year-old Castano went 1-2 with a 3.03 ERA in seven games (six starts) last season. Considered the fourth piece in the Marcell Ozuna trade with the Cardinals in 2017, he likely projects long term as a swingman on the staff, though manager Don Mattingly noted earlier in the week that the organization sees him as a starter.

Neidert followed Castano with two scoreless innings, permitting two hits and striking out the last batter he faced in Steven Souza Jr. Neidert, ranked as Miami's No. 11 prospect by MLB Pipeline, used his entire repertoire of fastballs, sliders, changeups and curveballs in the 31-pitch outing.

In 2020, the 24-year-old right-hander made the Opening Day roster as a reliever, but he missed time with COVID-19. He allowed 10 hits over 8 1/3 innings across four appearances in his first taste of the big leagues.

"Honestly, goal for me is always not to walk people and make them put it in play," Neidert said on Zoom. "No walks today, that was nice. Fell behind some hitters, and it was nice to see the fastball was playing well even when I couldn't get my other stuff on the plate. I had some bad swings on it, so that's always a very good plus sign."

Both rookies, who made their MLB debuts in 2020, had family in attendance. That wasn't possible upon their callups last season.

"[Castano] got ahead in the count for the most part all day," Mattingly said. "I thought he let them kind of back in counts the first inning, and then it was like, 'OK, I'm not doing that' and got ahead in the count, and then stayed attacking the second inning, which was better. So it was good to see him make that adjustment.

"I thought Nick was aggressive, didn't walk anybody, getting ahead in the count for the most part. Could have been better. But on the attack. So I liked both guys, Daniel especially that second inning when he got more aggressive and pitched to contact instead of getting ahead in the count and then kind of let them back into an offensive position."

Prospect watch

• JJ Bleday (No. 2) hit a homer to left-center in his second at-bat.

• Peyton Burdick (No. 16) was hit by a pitch.

• Nasim Nunez (No. 20) walked on four pitches and stole a base.

Tech alert

When the Marlins took batting practice at Roger Dean Chevrolet Stadium on Saturday, they tested out the electronic strike zone. Consider Mattingly a fan.

"I like it," Mattingly said. "It's quick, you get it instantly. MLB had some little phones that you were shown exact location of pitches. And it was instant, so you know, I liked it. I think there will be kinks to work out. And as technology just continues to get better and better, I think it gets more specific."

He said it

"We go out there and just have as much fun as we can. I don't know if you guys saw it today -- I threw a ball over to first base and everybody in the outfield and infield [were] screaming at me because it wasn't at Garrett Cooper's chest. We're just out there having fun, yelling at each other, trying to make the game as Little League as it can be. And that's how we're going to go out there and win." -- Jazz Chisholm

Up next

Right-hander Sandy Alcantara, Miami's 2020 Opening Day starter, will get the nod in the Marlins' spring home opener at 1:05 p.m. ET on Monday at Roger Dean Chevrolet Stadium. Right-hander Harol Gonzalez will start for the Mets.