okay for most trash pulls you wnat the CCers to opull from maximum range (about 20 yards.) the healer should be as far behind them as possible and you want to be behind the healer by about 25 yards. the CCers pull and runback, once the non-cc'ed mobs are seperated from the CC'ed ones you charge, because you're charging from max range your GCD comes off before you fininsh the charge, allowing you to Shockwave on the move, the mobs end up stunned , with you behind them, rend thunderclap and cleave at will as you should be far enough away that TC won't break things.
oh and remind any trigger happy DPS that you are not a ranged tank and it generally is a good idea to let you get within melee rage before firing off. good idead to mark what you want CCed (casters. ranged, anything that won't come to you)