I dont see CC as being that great of a pitcher personally. Sure he's only what, 24 or something, but I dont see him improving so much anymore.
In somewhat limited innings, he has a career 4.02 ERA and 480 K's (thats in 622 innings). Decent numbers, especially for a young guy, sure. But nothing amazing.
For comparison:
Kim is 25. (our Kim, our current 5th starter). In 410 innings he has a 3.27 ERA and 423 K's. Much more impressive numbers from a guy of about the same age if you ask me. I think our priority should be developing kim into a top notch pitcher, since he is absolutely capable of being one, not signing C.C Sabathia.