Originally Posted by Triples
I'll start the discussion with the notion that it depends on a lot of things like room at the next level, needs at the next levels
With respect to "needs at the next levels," to me, that's a consideration if and only if the level in question is the MLB club. It's nice to keep the affiliates happy by fielding competitive clubs, but the purpose of the farm system is to develop players for Cincinnati. I wouldn't care if Chattanooga had the worst outfield in professional baseball, it shouldn't be a factor in deciding whether Jay Bruce should be promoted. (If they had the best outfield, then you run into the "room at the next level" factor you mentioned, but an elite prospect rarely has to wait on another elite.)
Admittedly, it gets more complicated when it's the Reds that have the gaping black hole and the player is tearing up the high minors. But even then, "is he ready?" is a separate question from "do we need him?"