Sure it is. FIP itself and xFIP isn't (so much), but the process of converting runs to wins is incredibly random and has very little year to year correlation - and most importantly very little accuracy. Also, it depends on which WAR you are using. If I am not mistaken, someone mentioned that Greinke's WAR last year was 5 something, someone else said 2 something. WAR from BR uses ERA (or RA not sure) and WAR from Fan Graphs uses FIP. There is no unique WAR which adds another layer of confusion when there is only one FIP, one tRA, etc. You can use any run total you come up with, and then convert it to wins a hundred different ways. Like I said there's no sense in converting runs to wins. Especially the way fangraphs or anyone else out there does it. Converting runs to wins in a vacuum doesn't mean anything because removing players from those vacuums converts runs to wins in a different way, though hits, walks, etc still convert to runs in essentially the same way no matter if you remove the vacuum or not, so to speak. Not to mention the way everyone defines replacement level pitchers is simply wrong.