Aaaaanyway, as someone has already mentioned, "fun and taking people allong you like raiding with is more important", so hopefully you can improve as a group, which is much more satisfying to me than joining some pug where we silently steamroll everything. Just my 2c.
Good luck with the rest of the joint, plague wing has some lol-tastic moments in it
Just a comment after looking at the armoury of Stormrend, The spec he is currently logged out in seems a bit confused, just my personal opinion as he has gone far enough into the blood tree for hysteria... and yet missed it for imp blood presence, which imo for max dps seems nonsensical. Also there is a major glyph slot empty
You're other dpser's are definately a bit low overall.
From looking over them quickly without seeing how their specs are set up part of the problem to me looks to be rotation issues. As someone has already mentioned your dps warrior definately needs to sortout his rotation.
Also and I could e wrong here btw not over knowledgabe about locks, I assume your lock is destro spec looking at his abilities used, I'm not sure he should be using chaos bolt but more focusing on using conflagrate when its off cooldown ( which he hopefully has glyphed so that immolat is not consumed by it) and rest of time spaming incinerate whilst keeping his other dots up. Howver don't totally take my word on this as i say could be wrong.
I have no clue about dks but yours does seems to not be using his abilities properly along with aforementioned spec issues. As for the rest no doubt its similar.
So overall yes your dps need to sort themselves out and from what you've said its clearly not a gear issue but with them all an issue with rotation and possibly spec, and perhaps they have gemmed/enchanted themselves incorrectly which never helps. Why not point them towards the mmo class forums to search for some advice
Your lock is doing way to little damage with conflag. His uptime on immolate is 40%... He might not have conflag glyphed. He is also not using glyph of life tap. I assume, jusdging by his dps, his gear is not at the levels where he can drop lt glyph.
Im sure he is also gemmed/enchanted wrong, since 3k dps on that fight is VERY low, unless you are wearing blues/naxx gear.