One of the more contentious labels in baseball punditry is "ready for the majors," as the vagueness of the phrase implies different things to different people, and the expectations for the player that its used for are instantly elevated, often to unrealistic points for rookies who are still developing as they play at the highest level. Drew Pomeranz would be an excellent example, a pitcher who truly was "ready for the majors" when the Rockies acquired him in the Ubaldo Jimenez trade, but who certainly wasn't "ready to pitch as he's potentially capable of pitching in the majors."
It seems that some fans want teams to only call up prospects if they fall into the latter category, but that's almost never going to be the case, as the players will need to take the final steps of development by learning against the very best, in other words, against players already in the majors.
Rockies starter Drew Pomeranz lacks adaptability
Troy Renck's article in the first link does provide some interesting insight into the organizational thinking at this point, and the picture with regards to Jhoulys Chacin isn't pleasant, as he's lumped with Tyler Chatwood and Rob Scahill as "auditioning" in late summer starts to rest the arms of Pomeranz and others currently in the four man rotation. That said, Chatwood and Scahill are both under the radar assets in the system, and much like Pomeranz and Chacin himself are in a space where taking the next developmental step forward would make keeping them (and keep having them pitch every four or five days) an obvious decision.
That lack of obvious value would bring me back to the original point of this post, that being "ready for the majors" is not at all equivalent to being "an obvious asset in the majors" and the major issue with the Rockies in 2012 is that not one of the young pitchers on the roster has taken the step from "ready" to "obvious." In the last two and a half months, I'm hoping that at least one, and preferably two of these starters do, or the Rockies are likely in for similar struggles come 2013.