Peeling is a very overlooked aspect of group pvp. Some classes are better than others at taking damage. If I play with a Holy Priest partner, and I'm an Enhance Shaman, I'd much rather have the enemy attacking me, than attacking my partner. Obviously you can not taunt in PVP, but what you can do is snare the enemies attacking your priest friend, CC them, damage them.. do whatever you can to buy your priest friend those valuable seconds.
With the Classic beta now out it seems every related article somehow manages to spark the eternal war of "Vanilla was the best WoW sucks now" and "lol nostalgia goggles, Vanilla sucked, enjoy your two weeks of Classic". I have to say, even though I understand the principles behind the battle and the reasons people behave and talk this way... I actually REALLY don't get it on a deeper level.