I don't think we keep any of our 3 prospects on the big club, if the plan is to start them under 50-60% of the games. Maybe even under 70-75%.
I like Bregman at 3B, Mayer at SS and Story at 2B, but Story has looked better on D, of late, so maybe Mayer at 2B works, too.
Campbell could play 2B vs LHPs and maybe some CF vs RHPs, but I think Cora really loves Rafaela in CF FT, and I can't blame him. Duran should not be benched vs RHPs, so the only other place for Campbell to get 60-75% playing time would be 2B vs LHPs and some 1B vs RHPs. I'm not sure we try that, unless Toro struggles between now and Bregman's call-up, which is possible. Currently, he's 2 for his last 17, so maybe the decline has begun.