Ok, firstly while logs are useful for nitty gritty detail they don't give much bacground. Now i see here you have 11 attempts put in. Are these just the ones you recorded or were there previous ones? My guild spent about 50 attempts before we downed him the first time just for comparison statistic. Anyway, from the looks of your logs people are still getting a feel for the fight. While this is tedious, unfortunately it's nescacary, there is a LOT going on at once. I'll go through a few things I saw that were pure mental mistakes.
On a few attempts i saw a supernova go off. Now, i know this phase can get VERY hectic. Quite simply there is no room for improvisation in a transition phase. Not because it's bad to save your raids ass, but if somebody changes the way they react to a situation somebody else may decide to rely on them to do it the same way everytime and then you get a sneaky little guy getting to the hammer=Raid go boom. For Each position of the hammer you HAVE to make assignments of what is going to happen and when.
And don't forget that for the first transition you have to leave a tank with nothing to do since he will be preocupied for the second transition. If it helps your raid to practice assignments have that tank literally do nothing for the first transition just so DPS don't use that extra 8k dps or stun (depending on your tank) as a crutch and then parish to the next phase transition because the tank was tied up with the big adds doing his job. Now short of telling you my guilds full strategy (not a state secret, just timely and my gramar is bad enough without me explaining a WHOLE boss fight) I can't give to much advice on how to position your tanks. But whichever you chose for dealing with a small add both times, i would go for the one who will be able to tie up an add longest. As a prot warrior I have a nasty aray of stuns at my disposal, so what my guild has me do is go to the add farthest from the hammer if it's place on the right or to the add on the far right if it's place in middle or left. My function is to: Stun,DPS,Stun,DPS,Stun,DPS. If i do it right, it never gets to the lava and i'm sitting there very busy as my raid finishes and come to finish mine off and stack for seeds phase.
I see a lot of damage to lava trap eruption, now as the tank i'm not sure exactly how that particular mechanic is dealt with but i do know there are ways of minimizing it's damage. I can ask my guild about later today if you feel this would be helpful.
I also see damage taken to Engulfing Flame. You may need to emphasise that backpedaling is not a acceptable raid behaivior, nor is keybord turning. Right click, strafe.
I hope I was helpful in some way, if you are more curious about a specific mechanic feel free to ask.