Ramsden

One of the big problems I can see starting off is your shadow priests. First, you have three of them. This is not really recommended. Since shadowpriests are likely going to be your lowest dps, the more you bring, the more dps you have to make up. Secondly, they are not performing well at all. I can't comment much on their spell rotations or anything, but their dps is a good 200-300 below what it should be. I notice their gear is pretty lackluster but if they can't pull more, you need to drop one for someone with more dps.

Also, your shadow priests' dps/VT uptime is hurting your casters in the form of not returning enough mana to them. I notice both of the mages in your two best attempts had to use 5 or more ticks of evocation. This is bad. This is a large dps loss for mages. As for warlocks, Mephi's DPS is much lower than it should be. He has 4pt6 but Bannish is beating him on practically every attempt. On your best attempt, Bannish got 15 more shadowbolts in than Mephi. At an average SB of 3700 (not counting crits), that's 55.5k more damage that he would've done, which equates to somewhere between 100-200 more personal dps. There are many small things like this that would help you to increase your overall dps.

Stack heroisms where it counts. It looks like you used 2 in the warlock/spriest/one hunter (?) group on your last attempt. With your warlocks, this is not quite effective. I'd recommend giving 2 to your hunters or melee group, or mages. Also, 1643 dps for a fury warrior is pretty dismal. Both of your dps warriors need to step up their game (though I notice your MS warrior's gear is not exactly amazing).

All that said, it looks like many people in your raid are not geared well enough or geared correctly to do the dps. Some of them are, but others are lacking things like 4pt6 that would help them significantly.