It's a common issue that ranged mastermind pets like to run up to melee range to punch things instead of, you know, just sitting back and shooting them. I have a merc mastermind and it's insanely annoying watching my soldiers run up to a melee boss that i've locked down with an immobilize to slap him in the face. It also makes it really hard to keep them out of the range of AoE attacks, especially since they seem to disregard the stay command. I don't think that removing brawl would really cripple their damage potential that much, but it would be a nice boost in keeping them alive.