Outfielder Brett Jackson and third baseman Josh Vitters, the club's No. 2 and No. 10 prospects, according to MLB.com, are likely to get called up later on this season. But it's not a given, Hoyer said.
"Those guys need to force the issue, I would say," Hoyer said. "Like we talked about with [Anthony] Rizzo, when they sort of really prove to us that they're ready and make it clear, then I think that's something we'll see.
"We really wanted to make that a precedent, of when a prospect like that really bangs on the door, they get up here. Not hopefully because of an injury or hopefully because we want to give them a taste of it, you want it to be because they really earned it."
Jackson entered Saturday hitting .259 with 12 home runs and 10 triples, with Vitters hitting .304 with 13 homers and 50 RBIs.