Buy or Sell....Zack Greinke one of the most overrated players in baseball?

I really thought a move to the NL Central (with the Brewers offense behind him) would behove Greinke. His 7-2 record this year is only an indication of how good the Brewers offense is, and not how he's pitched. He's been TERRIBLE! His ERA is now over 5.60 after his shelling tonight. And outside of his Cy Young season he's been a pretty average pitcher in his career. I think i've completely overrated Greinke myself. What do you think?