I play 4 dks, ussualy have a friend healer with me.
90% winrate in Wsg since i got some gear.
What i do is that i rush for flag, pick it with main DK, then i run to middle, kill the horde flag carrier then i go and turn in the flag.
Repeat.
You shoudnt die really exept if you meet a premade. Practice makes good results, trust me :)