As far as more important stats than wins how about WAR, pitching WAR, walk to strike out ratio, WHIP, ERA +, adjusted run percentage, BAA and innings pitched to name a few.
Back to the Arietta argument, your ballpark claim doesnt hold water....you see since the 1940's they have come up with some stats that adjust for those types of things, and who leads MLB by a mile in ERA +, grienke. Adjusted runs, grienke. Adjusted wins, Greinke.
Enjoy the fact that Arietta is having a fantastic year, but nobody in baseball except cubs fans would ever claim he is currently THE best pitcher in baseball. It is border-line delusional. Even using your favorite stats alone, this year he is having his career best year by a mile ERA at 2.11. Kershaw's ERA is 1.94 over the last three years combined! Kershaw's career ERA is 2.45, Arrietta has never even had a SEASON with an ERA that low before this year. Kershaw is also 2 + years younger than Arietta and has 55 more wins.
Oh snap. Maybe you can embarrass me with more of your archaic baseball knowledge and once again anoint yourself CB's supreme baseball mind. Pretty brash claim, since I have yet to see any poster agree with your reasoning.