On heroic Blackhorn at the moment and having trouble with it. Am on the melee add's and the sapper as a priortiy, but if leave adds to get sapper, adds stay up. If stay on add's sapper gets through

just wondering if anything can do about it or anything I've missed. Have blade twisting on combat spec which is ok if get to the sapper but it's getting the first few hits onto him. Also should I be using wound psn with the amount of target swapping as don't seem to be on one or the other too long atm

We haven't got to second phase yet either
Have tried sub a few times and sometimes makes it easier to get to the sapper but, aint got the slow then and just runs on through
I'm usually the only melee & makeup is usually:
Shadow Priest , Resto Druid, Boomkin druid, 2xDK tanks, MM Hunter,Combat rogue(have sub spec), Warlock, Arcane Mage, 2nd Healer (disc priest atm/hpala mostly)
World of Logs - Real Time Raid Analysis Usually sun/mon we're on him past 2 weeks.