MIAMI -- When the Marlins optioned two of their top prospects -- outfielder Monte Harrison and right-hander Nick Neidert -- to Triple-A Wichita in late March, it appeared to end any realistic chance of either being on the Opening Day roster.

Much has changed during these unprecedented times.

With MLB reopening camps on Wednesday, new guidelines are in place for the 60-game season, which is scheduled to start on July 23 or 24.

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Now, not only are Harrison and Neidert realistic possibilities to be with the Marlins from Day 1 of the season, but so are many other players previously considered “on the bubble,” or even some once viewed as long shots. And with the 2020 Draft in the rear-view, potentially even the club's top pick could be an option.

This greatly increases the chances of left-handed pitching prospect Alex Vesia, ranked No. 27 on the club's Top 30 Prospects list, per MLB Pipeline, making the team -- either on Opening Day or at some point early in the season. Vesia, a non-roster invitee, impressed at Spring Training before it was shut down on March 12 due to the coronavirus outbreak.

More roster clarity will come on Sunday at 4 p.m. ET, when all teams must submit their list of 60 names for the player pool. Sunday also is the deadline for players to opt out of the season if they have health-related issues or apprehensions about participating in 2020.

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As part of MLB’s plan to reopen after being shut down for more than three months, roster composition will be different during the 60-game 2020 season.

The 60-person player pool is the group of players eligible to play for each team during the season. Per MLB’s Operations Manual, all players on the 40-man roster “that the Club anticipates participating” in the season will be part of the player pool.

Shortly after Harrison and Neidert were sent down in March, MLB rosters froze. The Marlins’ roster has been at 47 since then.

For Miami, the first major activity is expected on Sunday.

Several non-roster invitees still have a chance to be on the Opening Day roster, which will sit at 30 for the first two weeks of the season before shrinking to 28 after two weeks and later 26 after four.

Brad Boxberger, Ryan Cook, Aaron Northcraft, Josh A. Smith, Pat Venditte and Vesia were in the mix for bullpen spots when Spring Training halted. If any of them are part of the Opening Day roster, 40-man space must be created.

In terms of position players, infielders Gosuke Katoh, Sean Rodríguez and Eddy Alvarez, as well as outfielder Matt Kemp, are non-roster possibilities.

With a universal designated hitter in place for 2020, Kemp could fill that role. However, the veteran struggled in Spring Training, and he would have to show he could provide value when camps reopen.

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The Marlins also could make some trades, but only players who are part of the 60-man player pool are eligible to be dealt. And players acquired in trades must be assigned to a team’s player pool.

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In rounding out their player pool, the Marlins also could make a surprise move, as well as add some of their top prospects. Right-hander Max Meyer, the No. 3 overall pick in the MLB Draft this month, is close to finalizing his contract. The former University of Minnesota standout is considered close to being big league ready. And outfielder JJ Bleday, Miami's No. 2 prospect, could also be part of the player pool. Bleday isn't currently on the 40-man roster.

Prospects on the 40-man to consider are right-handers Sixto Sanchez (No. 1) and Edward Cabrera (No. 5), and shortstop Jazz Chisholm (No. 3).