"I don't think there's an exact science," Hinch said about moving Torkelson and Greene to Toledo. "You can't predict how things are going to be. You call them up, and they get off to a really hot start, then you kept them down there too long. You call them up and they get off to a dry spell and they're not very good early, then you rushed them. There's no perfect way to predict exactly how they're going to respond or what the right time is."
This article: Detroit Tigers promote Spencer Torkelson, Riley Greene, Ryan Kreidler to Triple-A Toledo (yahoo.com)
with A.J.HInch of the Detroit Tigers is about moving rookies from AA to AAA much less the Big Show.
This article shows moving these players around is not a simple -- Why aren't they moving so and so because I think they should -- so much rhetoric is about here but says why and how difficult it actually is to do so and not screw things up worse for the player or team. --- A good read.