JUPITER, Fla. -- There once was a time when young Peter O'Brien of Miami Gardens would have done anything to spend a Spring Training with the Marlins.

At 28 years old, O’Brien is finally getting his wish. The veteran first baseman, who made his Marlins debut last September, has a chance to cement himself as a regular starter for his childhood team.

“It’s a dream come true, it really is,” O’Brien said. “Growing up and watching the Fish play as a kid, then kind of playing for a couple different organizations and then finally finding my way back here, it’s a good feeling. It’s very comfortable.”

A former second-round Draft pick and touted prospect with the Yankees, O'Brien hit .273/.338/.530 with four home runs in 66 at-bats for the Marlins as September callup last season, splitting time at first base and in right field. Though his outfield experience at the Major League level is limited to only 21 games, O’Brien is competing for the starting right-field job.

O’Brien would also likely see reps at first base when Neil Walker or Garrett Cooper need a rest.

“I don’t think there’s an adjustment at all,” O’Brien said of playing both positions. “I’m ready for both and I played a lot of outfield in the past, so I’m really comfortable out there and I’m really comfortable at first base as well.”

It’s been a long road back to South Florida for O’Brien, who played his senior season for the University of Miami Hurricanes. A 2014 trade for now-teammate Martin Prado sent O’Brien from the Yankees to the D-backs, where he played before being dealt to the Royals in January of 2017. O'Brien lasted in Kansas City until May of that year, when he was claimed by the Reds before being claimed again -- this time by Texas -- after only five games in Triple-A.

Marlins manager Don Mattingly pointed out that not every top prospect has immediate, sustained success from the time they begin their professional career. Mattingly invoked Hall of Fame outfielder Ken Griffey Jr., who dominated the league for over a decade after debuting as a teenager in 1989, as the rare exception to the rule.

“It usually takes guys a little bit,” Mattingly said. “There’s usually an up-and-down in there -- sometimes there’s multiple up-and-downs -- and that’s what you look at when you get into the non-roster, six-year free agents. Some of these guys develop a little bit later, so you can pick up some guys like that who are still growing and getting better.”

O’Brien hit 23 homers between Double-A Jacksonville and Triple-A New Orleans before joining the big league roster last fall. His power has never been a problem -- O'Brien finished second in the Triple-A Home Run Derby in 2015 -- but plate discipline is an area that he and the Marlins are working on this spring.

“I’ve seen from the beginning that Peter is a guy that kind of understands who he is a little bit with his swing, his approach,” Mattingly said. “Guys have that type of power and get pitched a certain way and you start to understand how they pitch you differently.”

Exhibition plans

After naming Sandy Alcantara as the Marlins’ starter for Miami’s Grapefruit League opener against the Cardinals on Saturday, Mattingly said he expects Trevor Richards and Jose Urena to start Sunday and Monday.

Richards was 4-9 with a 4.42 ERA in 25 starts last year but struck out 130 hitters in 126 1/3 innings. Urena pitched to a 3.98 ERA, his second straight year with a sub-four ERA, in a team-high 31 starts.

Fully healthy

As injuries pop up in other camps, Mattingly doesn’t have to worry about serious ailments just yet. Mattingly said that the Marlins were “pretty good” with their current health.

“You’re always gonna have a little of this knick-knack stuff,” Mattingly said. “We’ve encouraged our guys to stay on top of anything they feel. … Don’t let missing a day turn into missing a week.”