Yup try two healing and ignoring weapons in all of phase 2. That's how my guild got the kill. If your DPS is very good, you will only get 1 empowered Whirling Corruption in phase 2 then 1 in P3. P3 adds you'll ignore while burning down the boss n taking care of MCs.
If it's your Prot Paladin taking your adds in P2, it's mostly likely high vengeance Eternal Flames pulling them, which is why he needs to toggle off Righteous Fury on the Whirl. Then he pops it back for P3 adds. If your Disc plays his DK, you might want to move into melee for MCs. So get used to a rotation of weapon drop > move in for MCs > move out to the next weapon drop spot, rinse n repeat till the transition. The last Whirling before the second transition, you won't get MCs after it, so you drop the weapon and you stay max range.
For p2 weapon placement, the easiest way for us was to have ranged run towards the stairs where garrosh was, drop the first weapon there, move in for MCs, then out to drop the next weapon right next to it, close to the wall. Tanks will have to move the boss along the middle to keep up with ranged, but no so close that the whirl hurts them.
Edit: ahh kinda too late with the tips
Good luck on your next try though