I just rank order who the target will be OTHER than BM, when on my Arms warrior.
is enemy Team BM/Fury? Go fury or healer
is enemy Team BM/Ret? Go ret or healer
is enemy Team BM/Mage? Go healer
is enemy Team BM/BM? Go healer
You get the idea. I trust my healer’s ability to keep us alive long enough to kill the ones supporting the hunter (running a rSham/War/sPriest 3’s).