I'd had a look at Webstats average dps values for a mage at my level (SSC) and it's 1900, mine is around 800-900 and I thought I was majorly slacking (and as I'm one of the top in my guild that we were vastly underperforming). I feel a bit better knowing we're probably around where we should be.
On-topic: I've never been to those fights, but from the ones I have experienced that are more about brains than big numbers (i.e. phase transitions at Hydross and Leo + inner demons) for phase transtitions showing the target of target should let you see who's not paying attention. I generally just tell everyone to watch their threat during transitions in an ever increasingly unhappy voice, reminding people that we're not going to do the fight if they keep pulling agro and also that things like health/mana pots or buffing cause threat too. If there's a persistant problem with a specific player either an officer or class leader will have a chat with them.
For the inner demons we asked if anyone was having problems with them (clearly those that died/got MC) so that a member of their class could help share tips. If we hadn't have sorted it out we would have resorted to webstats to find who was having problems.
I think it probably helps if you have someone who's vocal on vent (not necessarily shouting, just gentle reminders), I realise at you're level you probably don't want people who have to be hand-held through content, but depending on how harsh your guild is about member mentality and how easy it would be to replace your less pro-active raiders it might be worth just talking them through every step.
I think some people just need constant reminders to keep them focused on what's going on around them.
As for dps getting in that mind-set, I'll admit to being guilty of that too. Doesn't help that my bf is our MT. For example when I don't stop to think that maybe 4 6k crits on that collosus in a row, just after the tank pulled might not be a great idea. Or when I forget to factor in spell travel time and see a FB flying towards Leo just as he turns into a demon. Just try and remind people that a dead dpser doesn't dps and that a dead raid doesn't down bosses.
If symptoms persist I'd suggest looking carefully at webstats, you should be able to see from that who's persistantly not moving out of aoe effects and also it might show threat, but I can't say I've ever looked closely at that. If you check individual players you'll also be able to see if they are using their threat reducing abilities.
