Pro Tip: Have a hunter/lock/stupid low dpser sit on Ursula the whole fight from when she spawns. She the one who throws the barrel on the persons head with the highest threat (i.e. tank) and then forces the brewboss and everything else to go crazy on healers and dps. do this and you will succeed 100%.
Yes man I've been telling this to every group I am in. Been running with dps doing 10k-12k DPS so 90% of the time healer runs out of mana, also nobody attacks Ursula ever.