Consider someone in a support role (MG, Sniper, rifleman sniping): if this person is performing his duty, he won't be dying much, just because his position generally requires staying out of firefights.
Now consider someone in an assault role (usually, but not necessarily, an SMG): if that person is doing his job, he will probably be dying a lot, simply from the high likelyhood of being sniped, ambushed, etc. while moving on a position.
Also, consider the "lamer factor":
Enemy sniper is devastating a team, but is finally killed.
Lamer switches teams, throws himself into the queue.
Lamer gets sniper, wanders around for a while staying out of combat.
Enemy sniper has been neutralized, but lamer hasn't really done anything wrong.