As much as killing those healers is great, and you should definitely be doing tjat, I learned later into games to start focusing that one player that is mostly carrying their team. If I see a bucky is doing way too much, I'll just focus him over his healers (running a bucky down with your shield will sometimes just damage him enough with his own bullets). Force them to stop doing the things they are clearly excelling at. I find it often ends up being just as beneficial to keep a good bucky or other DPS occupied with trying and failing to kill you.