Well it all comes down on your raid setup and how you do it. We pack together and AoE them down before they even reach us, and I'm usually on the top3 going MM with 1 point on Rapid Killing for Rapid Recuperation procs (Beth'tilac style). I tried BM few tries but the main problem I found was pet positioning and his focus not regenerating for AoE if I keep him DPSing Ragnaros until adds pop, also I found BM DPS lackluster overall fight.
That's what I figured, I just get so bored of MM sometimes that I try to justify another spec lol. Thanks.