MIAMI -- On Friday, the Marlins officially signed their first-round Draft pick, outfielder JJ Bleday, and introduced him to the organization by having him take part in batting practice. A similar situation occurred on Saturday, with Competitive Balance Round A pick, outfielder Kameron Misner, and international free-agent shortstop prospects Jose Salas Jr. and Ian Lewis taking part in warmups with the big league club.

Perhaps the next way the Marlins will infuse new players into their system will be through the trade market.

The July 31 MLB Trade Deadline is a little more than two weeks away, and the Marlins, who dropped Sunday afternoon's series finale to the Mets, 6-2, continue to explore ways to make moves. Nothing is considered close as teams are still measuring the market.

Prime candidates on the Marlins to be dealt by the end of the month are veterans who have expiring contracts after the season -- closer Sergio Romo, infielder Neil Walker and outfielder Curtis Granderson.

All three have proven track records and playoff experience.

This weekend at Marlins Park, at least eight clubs have been scouting the Marlins-Mets series, with many targeting pitchers from both teams. The Yankees, for instance, were on hand to scout right-hander Noah Syndergaard’s start for the Mets on Saturday.

The Marlins are open to listening to inquiries about their starting pitchers, but they are less likely to be dealt by the end of the month than some relievers. The A’s, for example, have been represented at Marlins Park, and they are seeking bullpen help.

Romo, 36, has 16 saves and is signed for $2.5 million. Walker, 33, is making $2 million, and is a switch-hitter who can play first, second and third. Granderson, 38, is signed for $1.75 million.

The Marlins are open to moving second baseman Starlin Castro, who is making $11 million this year, and has a club option of $16 million for 2020, with a $1 million buyout.

Miami has not engaged in any serious trade discussions for Castro, as most of the conversations have been exploratory.

Injury updates

Infielder Martin Prado (right hamstring strain) had his rehab assignment transferred to Double-A Jacksonville. The veteran had been at Class A Advanced Jupiter.

Prado is scheduled to play seven innings at first base on Sunday for Jacksonville in Game 2 of a doubleheader. He also will see time at third.

“He’s been playing a little bit already in Jupiter,” Marlins manager Don Mattingly said. “He’s had 12 at-bats, probably going to get another 15 or so. He should be ready soon, if everything goes well. He’s getting close.”

Riddle struggles

JT Riddle has had his struggles at the plate as well as in adapting to center field, which is a work in progress from his natural shortstop position. He was out of the starting lineup on Sunday after his average dipped to .192 with a strikeout rate of 29.9 percent.

“He’s kind of all or nothing at the plate right now,” Mattingly said. “Swing and miss, not really controlling the strike zone. Center has been fine. Last night [a misplay with right fielder Brian Anderson], it might have just been a miscommunication. He’s not a loud guy. He’s got to be loud out there. Take charge, really get the other guy off the ball if he wants it. He waited until the last second and went ‘I got it! I got it!’ Not really good at any ball that’s in between.”