I understand what you're getting at, but I don't really see it that way. Overall what matters is the net effect a given player has on your team. Obviously, there are cases where you can cover up one guy's deficiencies (i.e. maybe a super awesome CF can cover for the guys next to him), but by and large, what matters is how many net runs that player gets you. Doesn't really matter where it happens (although, obviously, with offensive metrics being more reliable, offense is easier to predict/measure the effect of). You may not see it that way, but I'm sure most of the GMs do. Most of the DHs in the AL were playing regularly somewhere in the field before they became a DH. And this is relevant because....? Most of them are (and have been) one dimensional players their whole careers. The Adam Dunns of the world were butchers at every position they ever played.