We were using the 2 at the front and one at the back for the start of our p4 attempts, then switched to 1 at the front and 2 at the back for the breadths, it helped us not geysering.
We also started in our formation at the start of p4 before he came up.
http://img683.imageshack.us/img683/6...ingvictory.jpg (ignore the names)
In the picture it shows our groups at the start of p4 before he rises. The coloured lines/circles are possible breadth of frost locations/areas and who would get there first depending on how long the line is, assuming everyone heads directly there as to not geyser the raid by just standing around, causing more healing and possibly too much damage through superheated aswell. The rag tank needs to blow a large cd while moving.
In that pic it was 2 melee dps and a tank at the front, 2 healers at the back left and a tank, and 3 rdps on the right.
We planned for two meteors at that stage but when the nerf came it ended up being one. The dk tank would be assigned to knocking back both meteors when he wasn't tanking, and when he was 2 rdps would be responsible for them.
This fight is extremely less stressful if you can get 1 meteor heading into p4 as to the length of the fight up untill that point.
Remember to always enter the breadth from the back of it as to not geyser, I remember starting off in p4 that was the next checkpoint you had to get past.
It depends on your raid comp as to why you aren't pushing 1 meteor. We had an average of 32k dps over our 6 dps, not including tanks and disc priest smite, or 220k raid dps in 99 seconds before the 2nd meteor would spawn which would push 1 meteor, with a demo lock (moonwell chalice+doomguard) and elemental shaman dominating.
What is your dps lineup?
It could also have something to do with your 2nd transition. This is the most important for pushing 1 meteor. If you push the boss to 41% just before the engulfing after u kill the 3rd seeds you stop dps, let him cast engulfing and then burn him. ON very good attempts we were pushing to 35%, on our kill it was 36%.
The scions are also pretty important, are they both dead by the end of the transition? If not you need to really push your dps on those, only killing the last son at around 44 seconds into the transition.
hope some of this helps