This kind of things is fine in solo, or to an extent in group content where people have no interactions at all with each other. But not in something where sometimes your worst ennemies are your other group members, where complex mechanics are involved, and where loopholes will be find very quickly.

In a similar thread (http://forum.square-enix.com/ffxiv/t...formance-Grade) i didn't get an answer, most likely because all is not as simple as it might seems :

I can't even see how SE could do something so complex depending of what can happen, and how people will troll with or abuse flaws in this kind of system.

Example 1 : a stack marker appear on someone else, i go stack with him but everyone else is staying away, so i get killed for doing the mechanic properly. Do you count my death as a bad thing or a good one ? How do you handle my dps loss that ensue (cause no mana left and death debuff) while i did nothing wrong ?

Example 2 : if someone else keep following me with his aoe marker and get us both killed, are you removing points from me ? As in 1 how do you handle my dps loss ?

Example 3 : how do you deal with people getting killed so often that i sometimes get out of mana on my rdm rezzing them ? Should i get points removed for not being able to dps anymore with lucid still on cooldown, while i did a good thing rezzing these two healers hoping that they will save the raid ?

Example 4 : if i know i can survive an avoidable aoe, should i getting points removed for staying in it so that i can dps more ?

Example 5 : the tank turn shortly the boss towards the group, i get cleaved and killed while the tank is still alive. Who do you remove points from ?

Example 6 : the tank start to run everywhere with a big group of mobs. Do you take points from me as a MCH because i can't dps with my bishop turret properly, and keep wasting 10 seconds cooldowns because the tank can't stay still ?

Example 7 : if there is personnal rewards involved, how do you deal with people being killed on purpose so that their healer friend can get a good grade rezzing them multiple times ?

If you can't even answer these simple questions (and i am sure we can find way more of them), then maybe a duty performance grade is not as good an idea as you think.