Its also a strat issue.
The easiest strat:
Pull him to a point 90 degree from where he starts I usually take the right side. Keep him face at the 45 degree from the centre of the circle on the line you pulled him. DO NOT MOVE.
Your healer stands max heal range to you between the centre and the doorway you came in. If you are max heal range he is outside the silence range as the boss is futher away.
OT hangs out where boss was at start because thats where the add spawns.
Very basic no moving and easy for everyone.
** Remember Warcraft players fail in directions you never thought possible.