1) Never give just one fight as a log example. Especially a fight with periods of downtime where ticks of DoTs will be hitting for little damage as you'll be unable to channel Malefic Grasp creating abysmal DPS. Notice in your parses you have periods of 0 damage (likely transition phases).
2) Without criticizing your entire group one by one, you are playing with some rather horrid players. Your Elemental Shaman pushed 30k DPS during active combat while averaging 14k overall. You have people dying during Attenuation, mostly your Shamans, but this is inexcusable. Alright, I'm going to look at everyone compared to the 200th best parse on record for the normal encounter of that fight and show the DPS comparable one by one:
Bisson - 15.3%
Asmodaie - 59.4%
Brewbear - 51.7%
Ozias - 29.2%
Dirttnasty - 39.8%
Veritas - 68.1%
Those are really, really bad scores for an overall group.
3) You provided no data on your reforging. It would appear, through some amount of knowledge of Affliction, that you're not that deep into Mastery. Mastery empowers your DoTs, and since Agony has a higher spell coefficient, if you never let Agony fall off, it'll do the most damage. I'm seeing periods of where you do no DPS meaning you let Agony fall off. Since MG works in sync with your actual DoT ticks, losing the damage on your MG ticks of your DoTs is why you see all 3 of your DoTs hitting harder than your MG DoTs by a wide margin.
4) I'm going to hyper analyze this one log here for you, personally, on this fight to show you grounds to improve.
4a) DoT uptimes are 91.1%, 92.6%, and 85.0%. These need to go up, up, and up. Recast DoTs before platform changes to see that DoTs do not fall off. Recast DoTs before Attenuation if you're not coordinated to avoid dying and do DPS. Never ever ever let Agony fall off.
4b) Why is there Rain of Fire in your damage parse here? You had 114 ticks totalling 791k damage. That is a lot of DPS loss as I can't see ANYWHERE there is more than 1 target to DPS aside from the mind-controlled teammates on the 3rd platform. Using Rain of Fire to break your teammates out is as effective as using your Hearthstone. Cast Haunt or stick to DPSing the boss...Affliction isn't worthwhile here.
4c) Fel Flame...remove this from your bar and quit using it.
4d) Drain Life...remove this from your bar and let your healers heal you (exception if you used it when all of your Shaman healers died to Attenuation
4e) You casted Dark Soul only 4 times during a 10 minute fight. With the assumption you don't have your 4pc, it's a 2 minute CD which means you SHOULD have used it at the following: (T = time)
T = 0:00
T = 2:00
T = 4:00
T = 6:00
T = 8:00
T = 10:00
Granted that last one may not have happened as the boss died at 10:02, but you should have AT LEAST gotten a 5th one in there somewhere.
It appears you are hit capped, so I can only wonder what your other stats look like. You have an abysmal crit proc rate in your logs, so that's promising. Overall, it looks like you need to work on your class mechanics before preparing for raid mechanics. You can do this at a target dummy, so work on keeping your DoTs up 99.5% of the time over 5 minutes with no movement. Once you get that down, start practicing keeping all DoTs up on 2 targets. Then start working in your CDs and learn when best to time things. Also, get the Affdots addon. Raiding without it as Affliction is just silly.