With all the DPS e-peening going around in WoW I figured I'd at least try to see what this whole DPS thing is about and how it actually relates to damage.
Normally you'd think if you have 600 DPS then you do 600 damage per second which would translate to roughly 36000 damage per minute and so forth.
Now as you may or may not know I have been using recount to record most of the boss fights and various battles and I recently have been paying attention to the figures of DPS vs Damage done in places like Karazhan with groups that are mostly in or around kara in terms of gearing.
What we see from those figures is that it is indeed regularly possible for someone to output a large amount of DPS and still generate comparatively little in damage out and that someone with significantly lower DPS generates comparatively high damage out.
Assuming that all the damage meters I have tested so far aren't completely broken we will have to explain how it is possible for someone to generate say 300+ DPS and still be #1 on the damage charts whilst someone with 600+ DPS only comes in #2
Lets take a step back first and state that everyone dies the same amount of times, the gearing between players are pretty much equal (as far as that's comparable) and all players are doing their best to output the most damage they can (no slackers, afkers, nosepickers, clueless people etc.)
In general most damage meters calculate DPS over the amount of damage you do. Most damage meters have been adjusted to also take in account a certain time window over which DPS is calculated. So assume you're blasting your target with whatever you're using causing x damage over y seconds. DPS will then be calculated by diving x by y.
Where y is your measurement window (5 seconds for example). If you're running around not doing any damage at all then this will not affect your dps (otherwise most people would have <10 dps after sitting around for an hour which is simply not the case in any damage meter I've seen so far).
And this is where the crux of the matter lies. A hunter (just an example) will output significantly higher dps if you check dps over a period when he's actually doing damage. If the hunter does no damage for the time window y then this does not affect his DPS in any way. That's the nature of the calculation.
Which also means that if the hunter goes out and shoots someone with a single arrow and then sits around doing nothing for the rest of the measurement window y then his DPS will be crap for that measurement and his DPS average will be lowered accordingly.
Makes sense so far doesn't it?
Now consider this: The hunter shoots the target with some kind of poisonous arrow that ticks away slowly for x damage per second.
Unfortunately right after he has to make a run for it because some nasty blizzard is coming his way or he needs to get out of a volcano. So naturally his DPS will be lower, because thanks to the poisonous arrow he is in fact doing damage which does result in DPS calculations being made (as opposed to no calculation being made if he doesn't do damage).
Of course the DPS for those 5-10 seconds he's running around will be terrible, but it is in fact measured and averaged out with his overall dps because that poison is ticking away for whatever damage it does per second.
Now lets take this step further and look at a 'Damage over Time' heavy class like a warlock.
Generally warlocks dot up a target and then proceed to pelting it with whatever spell they like to use (shadow bolts for example).
Now whilst he is pelting shadow bolts and his dots are ticking away the warlocks DPS is calculated by adding the damage of all the dots and the shadow bolt hits in the measurement window y and then deviding it by y.
Now it's the warlocks turn to move but his DPS calculation continues because his dots are still on the target.
This is good stuff since you're still outputting damage, but really bad for your DPS calculation because it is only calculated over the dot damage which is generally low but consistent over a longer period.
Now consider fights where there is a lot of movement (shade of aran for example). Warlocks will still dot up their target thus forcing DPS calculations. Hunters will generally run around and squeeze out a few damage 'spells' resulting in DPS calculations only when he/she is actually doing damage.
This means on average the hunter's dps will be as high as always (burst damage) but for the warlock counterpart the DPS calculations were mostly done over ticking dots rather than dots ticking and the usual shadow bolt spam.
Which in returns results in the warlocks DPS slowly degrading to the 'pure' DPS from the dots whilst the hunter simply skips a few DPS calculations because he's not doing damage at all.
The warlock however is continually doing damage. And no matter how little the damage from dots is it will add up over time thus resulting in a much larger damage done figure.
So yes... you can do 300DPS and still be #1 on the damage list and yes... you can output 600+DPS and still be on the bottom of the damage list.
DPS is a normalization that can help show how you are doing compared to other players preferably of the same class not a way to rate people's equipment, effectiveness or skill.
For that you will simply have to go take them to an instance and look at the damage that was actually done.