WEST PALM BEACH, Fla. -- Now in his third big league camp with the Marlins, Isan Díaz is comfortable with his standing in the organization. The 23-year-old is part of a young core of promising players, and he projects to be a big league regular at second base.

In his mind, he considers himself the starting second baseman right now. But Díaz also is aware that isn’t his call.

• Box score: Marlins 7, Astros 4

Spring Training likely will go a long way in determining whether Díaz is at second base on Opening Day against the Phillies on March 26 at Marlins Park, or if he starts off at Triple-A Wichita.

“I come in every day as, ‘I’m the second baseman,’” Díaz said. “This is where I want to play, and this is where I want to be. Obviously, that’s what my goals are, and what I’m looking forward to the most.

“But, obviously, the front office and [coaches], they make their decisions. Whatever happens from there, happens.”

A strong Spring Training by Díaz should make that matter moot.

On Tuesday at the Astros, Díaz was hitless in two at-bats.

“I think Isan is comfortable as far as what to expect,” manager Don Mattingly said. “But I think also he knows that he has to compete. He looks good.”

Díaz got a taste of the big leagues last August, at age 23, and had a standout season at Triple-A, hitting .305 with 26 home runs and 70 RBIs in 102 games.

In his MLB debut, the left-handed-hitting second baseman had an unforgettable moment, homering off Mets ace Jacob deGrom. The blast to right at Citi Field came while his father was being interviewed by Fox Sports Florida, making the home run a viral, national sports moment.

But Díaz’s 49 games in the big leagues were filled with highs and lows, and he had a slash line of .173/.259/.307 with five home runs and 23 RBIs in 201 plate appearances.

“It was a rollercoaster,” Díaz said. “It was up and down. I had good nights. I had bad nights. But it was all a learning curve.

“I was happy that I was able to come up and get a taste of it. Now I know what to expect, and what it’s like up here. Just the day-to-day things that happen in the big leagues.”

This spring, Díaz is more mature and prepared for the task ahead, which is to round out into a big league regular.

From a year ago, he is carrying with him all the words of advice from former Marlins veterans like Curtis Granderson, Neil Walker, Martín Prado and Starlin Castro.

“They leave things that kind of stick with you,” Díaz said. “They teach you things that kind of help you along the way.”

A year ago, Díaz would let the bad times linger and weigh on him. Now, he’s striving to roll with the punches.

“I used to really hold on to what happened 24 hours ago, rather than just leave it and move on,” he said. “It’s something that really stuck with me.”

The fact Díaz had rookie struggles didn’t surprise Mattingly, or the Marlins, in general. More times than not, young players struggle for at least a while before they adjust to the grind of the big leagues.

“I think in general, it usually doesn’t go that well,” Mattingly said. “You see some good, but very few guys take off right away.”

The Marlins are so confident Díaz is headed for a bright future because of his foundation. He has the ability to hit and a track record of being impactful.

“I always go back to the basics,” Mattingly said. “Isan’s got a good swing. He’s able to use the whole field. He sees the ball good. So, from that offensive side, you really think it’s going to be there.”