When you trade up, you put a lot of chips on ONE GUY being really good (and staying healthy), because you've given up other players to get him.
In the Bills' situation, if anything, you trade DOWN. Your best course of action is not to pursue ONE dominant player, you need SEVERAL good ones. You get your hands on several by adding picks, not giving them away. Plus the strength of your organization (we hope) is now Buddy Nix - get more picks in that man's hands!!!!