Bush's 4.43-4.91 xFIP the past 3 years is probably pretty accurate. He really is a #3/#4 type guy, your original argument just seemed a bit out there becasue WAR is a result based stat just like ERA. tRA is as well(it ignores the fact that HR/FB is a largely random function and ignores BABIP as well so it ultimately isn't useful when trying to decide how good a pitcher is), none of these stats can tell you how good a pitcher is, they tell you how well he happened to pitch over a small sample and those things are very different. Bush is not a close to replacement pitcher, he isn't a good pitcher either. He is not the type of guy we should just let go for no reason though which seemed to be your intent. As for WAR not being good enough for me, even if you look at WAR it suggests that over the past 3 years Bush has been well above replacement level.