There is no stat by itself that is end all be all or even close. There are just some better than others. In this case, if we're looking at how pitchers might perform going forward (i.e., who should stay in the rotation), xFIP might be best. http://www.fangraphs.com/library/pitching/xfip/ 'Why xFIP: While the value of moving from ERA to FIP is that it attempts to strip out defense, luck, and sequencing, moving from FIP to xFIP is useful because it tries to remove some of the randomness in the pitcher’s actual performance. Everything we do to calculate FIP is based on the idea that the pitcher is responsible for strikeouts, walks, hit batters, and home runs while the defense is not. This makes FIP a better indicator of pitcher performance than ERA.' 'Expected Fielding Independent Pitching (xFIP) is a regressed version of Fielding Independent Pitching (FIP), developed by Dave Studeman from The Hardball Times. It’s calculated in the same way as FIP, except it replaces a pitcher’s home run total with an estimate of how many home runs they should have allowed given the number of fly balls they surrendered while assuming a league average home run to fly ball percentage (between 9 and 10% depending on the year).' 'In a very simple sense, FIP tells you how a pitcher has performed (value) independent of their defense, while xFIP tells you about how well he has pitched (ability, talent) independent of their defense.'-- That is why xFIP is a better predictive stat (cause pitchers are usually expected to pitch to ability and talent), while FIP is a better stat to say how a pitcher has performed.