All statistics have inherent flaws. W/L is tied into run support. Absolutely. WHIP has flaws because it regards a homerun and walk as the same thing. It also has no calculation of how effective a pitcher is in getting out of jams. Strikeouts is a great statistic by fans but is even more meaningless. By sheer strikeouts, Nolan Ryan was the best pitcher ever. I doubt anyone would have Ryan on their top 5 best pitchers of all-time lists, however. And that is largely due to his career mediocre W/L record. ERA can also be influenced by run support, too. A pitcher in a 2-1 pitchers duel is probably concentrating a little more than a pitcher in an 8-0 game. Look at Arrieta against the Giants last week. Throught 5 innings he was un-hittable. The Cubs then blew the game open and Arrieta allowed a couple of hits in the 6th inning. Do you think had the score been 1-0 or 2-0 he would have had a little more urgency in his pitching in the 6th inning? Of course, that's human nature.

Jake Arrieta is top 5 in baseball in Wins, ERA, BAA, WHIP, CG, shutouts. No other pitcher in baseball has a resume that can say that. He's 1st in wins and 2nd in ERA. He's the best pitcher in baseball right now. Tough to argue otherwise.