1. Zack Greinke, LAD   1.66
2. Jake Arrieta, CHC   1.77
 
NL WINS   W
1. Jake Arrieta, CHC   22
2. Zack Greinke, LAD   19
Arrieta also has more innings pitched and more k's
Arrieta also has more losses.  6 to Greinke's 3. I think if Greinke gets his 20th win with only 3 losses it's a lock. 
I don't get to vote on it, but I'm thinking the voters will go with Grienke. 
If I'm wrong, I'm wrong. It's a subjective analysis. 
Since the All Star break Arrieta has had the best ERA for a 1/2 of baseball in history, but like I said. I don't know if it's enough over Greinke his win / loss numbers and his ERA. 
*Update. Greinke just got his 19th win last night... My mistake. I'm not sure it changes much, 3 losses is a dynamite year, but we will see what the voters say of course.*
I'd say that there's 3 or 4 outstanding pitchers this year in the NL alone.