JUPITER, Fla. -- Prospects weren't the only ones this week taking part in the Marlins' three-day hitter's camp at the Roger Dean Chevrolet Stadium complex. Peter O'Brien and Garrett Cooper, who are competing for Opening Day roster spots, joined the group of position-player prospects invited to the minicamp.
Infielder Miguel Rojas, a third Major League veteran, also showed up to get some early work.
"It's great to have those guys out here with those younger players around them," Marlins vice president of player development and scouting Gary Denbo said. "Those guys are here voluntarily. They're going to be coming out three days a week. They're going to be around our younger players."
For O'Brien and Cooper, especially, getting a head start on Spring Training is important. The two are in the mix for the starting first-base job, and both can play corner outfield. O'Brien has caught in his pro career, as well, and could fill in as an emergency catcher.
Cooper, 28, is recovering from right wrist surgery, and he is still getting back into game shape. Monday was the first time the 6-foot-6 right-handed hitter took batting practice on the field.
"He's been in the cage up until this point," Denbo said. "I think he looked great. The ball was coming off the bat really good."

Miami's Opening Day right fielder in 2018, Cooper was struck by a pitch on his right wrist in the second game of the season, and he dealt with the injury all season. On Aug. 31, Cooper underwent surgery. He appeared in just 14 big league games, and hit .212 in just 33 at-bats.
If healthy, Cooper could have an impactful role for Miami -- either at first, in the outfield or off the bench.

O'Brien, 28, has put himself in an interesting position, because he opened eyes within the organization as a September callup, and followed that up with an impressive showing at the Dominican Winter League.
The Marlins are still in the trade and free-agent markets looking for a first baseman, but as things stand, O'Brien is the likely front-runner to start.
"He spent about a month in winter ball this year," Denbo said. "That's something that you won't see a lot of Major League players doing. He went down there and spent a month. Worked on plate discipline and worked on shortening up his swing and putting the ball in play more often. He did really well down there and accomplished his objectives. Now, he's back here ready to go and trying to make our Major League team."
In 15 games and 50 at-bats in the Dominican Republic, O'Brien hit .359 with two home runs and 11 RBIs.
With Miami in September, the Miami native hit .273/.338/.530 with four home runs, five doubles and 10 RBIs. O'Brien, who attended the University of Miami, was drafted by the Yankees in the second round in 2012. Denbo was with New York at the time.

"I've watched him closely over the years," Denbo said. "When he became available last year, we jumped on him. There's not many people in professional baseball who impact the ball like Peter O'Brien does. He does it almost effortlessly. It doesn't look like he's trying to hit the ball out of the ballpark. The ball jumps off his bat, and the exit velocities coming off his bat show that he's one of the top guys in baseball."
O'Brien's average exit velocity with the Marlins was 92.1 mph, according to Statcast™. He had 23 balls in play last September logged as hard contact -- 95 mph or higher. Eleven of those balls were 105 mph or higher, with a high of 112.2 mph.