I think this is an exploit not completely sure about it but i'll give it a try
While being in AV I noticed that I could cast Pain Suppression on Drek and Galvanger. Why it's nice? It lowers the dps on the boss and can give you a win if horde/ally fights at same time.
You can prolly also use this on the Alliance Bosses but didnt tryed there.
Why I think its exploit? Becuz normally u cant cast PS on Bosses/NPC's
Paladins could also try "Divine Intervention" and give them a 3min immune buff
or bubble the boss so no melee can hit him anymore and tanks might lose aggro and lowers dps and stuns
I hope it's helpfull for all you ppl out there who keep losing AV, just get a few priests to defend and spam PS on boss