Whether top Red Sox prospects Roman Anthony, Kristian Campbell or Marcelo Mayer make the Opening Day roster continues to be a major storyline of spring training.

But Red Sox manager Alex Cora made it clear for that to happen it would have to come under the right circumstances.

The Red Sox will not have any one of the “Big Three” on the big-league roster for ceremonial purposes. They will need to win an everyday job to play in the majors because serving in a platoon role is out of the question.

“I think it’s fair to say it,” Cora told reporters Sunday, per MLB.com’s Ian Browne. “There’s still development, but at the same time you see it. But that at-bat yesterday by Roman against the lefty, that was a mature bat, and we’ve seen that through camp. He played some good outfield in Jupiter. He moved well. Marcelo’s doing the same thing. Campbell has struggled. That’s part of it, right? Like, not everybody is going to be able to slow it down in camp and be perfect, but that’s part of the progression.”

Anthony, who is considered the top position prospect in all of baseball, perhaps is the closest of three to cracking Boston’s roster out of camp. But there’s no room in the outfield at the moment for the 20-year-old with Jarren Duran, Ceddanne Rafaela and Wilyer Abreu, who expects to be ready for Opening Day despite missing time this spring due to a virus, taking up the three starting spots.

Mayer showed well so far this spring, slashing .360/.429/.989 with one home run and seven RBIs. But the 22-year-old shortstop ran into the same problem as Anthony. There’s not an open spot on the left side of the infield for Mayer to fill with Trevor Story and Alex Bregman set to be Boston’s starting shortstop and third baseman, respectively.

Then there’s Campbell, who had the best shot out of any of the prospects to crack the roster due to the opening at second base. But Campbell hasn’t seized his opportunity, batting just .152 in spring training. Meanwhile, David Hamilton looks like the favorite at the middle infield spot after blasting two home runs with six RBIs and five stolen bases.

It’s looking more and more likely that Anthony, Mayer and Campbell will begin the season with Triple-A Worcester as the Red Sox try to juggle what’s best for that prized trio and their big-league club.

“Playing time is important, the development of the player is important, but I think winning games right now is more important,” Cora said.