A few years ago when the Cubs were struggling for pitching and names like Rich Hill and Sean Marshall came onto the scene. But a young man, converted catcher, who threw a hell of a curveball named Juan Mateo also had a few starts and looked realy impressive. He had some control issues, which was why he didn't make the rotation last year, along with the signings of Ted Lilly and Jason Marquis and the "return" of Wade Miller. But what's happened to him since?

http://www.baseball-reference.com/boxes/CIN/CIN200609240.shtml
I remember watching this game against the Reds and he had great control of his curve over the outside corner, making Griffey swing and miss once on it. You can see the 4 walks to the 4 strikeouts, showing the control problems.

He has great stuff though and I think you have to consider him if he is healthy