Please guys, we need to get over this idea that wins are the end-all-be-all of pitching stats. Have a look at this: 2012 MLB Baseball Pitching Statistics and League Leaders - Major League Baseball - ESPN
This is a list of pitchers sorted by the average runs scored in support
of them. Take a look at who's number 3.
Now take a look at where Cueto is. Take a look at where Kershaw is. Do my eyes deceive me? Nope. Neither of those guys is in the top 40
of run support in the National League.
18 wins looks very nice, indeed. But put Gio on the Mariners or the Astros and I don't think it's very likely he has the same success.