There are multiple threads on the topic of fake tanks/healers ruining the experience. In this thread I want to focus on solutions that ZOS can implement with low maintenance costs if done right (so no requirement for GMs checking reports), and options that would not result in worse dungeon experiences (like damage debuffs on healers/tanks that could otherwise have carried a bad group). Feel free to add your suggestions if you can think of such that qualify.
I see 2 such solutions:
a) The easiest solution to this problem would be to add the option to queue for a non-traditional group setup. Add a checkbox in the dungeon finder, and only put people who have it selected in non-traditional groups, and only if there is a long queue for the role they selected. There is literally no reason not to implement this, even if my other suggestion is also implemented...
b) Create 3 "Undaunted Proving Grounds" (one for each role). Could be a new free DLC (like homestead and 1T were). They should in their atmosphere be like arenas or the Blessed Crucible dungeon, but only contain painfully obvious mechanics that are present in almost every dungeon, and grant people a score depending on how well they do there in various aspects of a certain role.
From here on out I'll be focusing on solution b) since a) is fairly obvious. If you already have an idea of how and why b) would work, feel free to stop reading here, there are no more suggestions, just details and reasoning for b).
For example for DDs the undaunted proving grounds could have mechanics like this:
1. A big boss with a fairly high amount of HP (to make sure power creep doesn't make this completely useless in the future) attacks an NPC ally. Your goal is to kill the boss before your ally does. Occasionally there are fairly easily avoidable and obvious mechanics appearing that do a lot of damage or even 1-shot you (for example red circles, boss turning around and starting to cast an interruptable skill etc). You get score not just based on whether you kill the boss before he kills your ally, but also based on how fast you kill the boss and how well you avoided the damage.
2. You get swarmed by adds with higher and higher HP that do quite low damage that adds up slowly to brutal levels if you stay alive long enough but can't kill adds fast enough. You get score based on how many adds you kill before you get overwhelmed.
3. You get a lot of ranged adds that keep moving around. You get score the same way as in 2.
This way you get to test damage on single target, AoE, and on moving targets.
For tanks it could look like:
1. Boss does a series of heavy attacks and after each heavy attack his damage increases by say 5%. There are also some easily identifiable mechanics like for DDs. You get a score based on how long you stay alive.
2. You get multiple NPCs as allies, and you get swarmed by adds that run off to attack your allies if you lose taunt. Your allies also do some damage (the more the better you debuff the enemies). They do fairly low damage to you (but frequently, and there will be more and more of them). Your allies are killing them, but slower than they spawn. You get a score based on how long you and your allies stay alive.
This way you test tank survival, add control, sustain and maybe even off-heal if the number of adds and their strength is balanced properly (so that you can prioritize the heavy hitters, which is also useful in dungeons).
I'm not an expert on healing, but it could be something like:
1. Adds of varying strength spawn, faster than the NPCs helping you could kill them. The adds prioritize attacking the NPCs, but occasionally some of them might run to you too. If you give buffs and debuffs increasing damage or resource sustain, they do more damage and kill the adds faster. There are also easily avoidable and well telegraphed mechanics going on just like for tanks and DDs. You get score based on how long you and your NPC friends stay alive (say score ticks with a timer and each tick is multiplied by the number of allies alive in the given segment). The damage that the NPCs do should be so high that no matter how good you'd be as a DD, you're better off being a healer and/or you get a debuff that makes sure that every attack you do does just 1 point of damage (to still allow the healer to trigger off-balance with lightning blockade and the likes, but not allowing to meaningfully contribute to the damage output).
This way you test buffing, healing and sustain.
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The 2nd part of the implementation of the proving grounds would be to sort dungeons by their requirements. For example assign to vet Direfrost Keep a score equivalent of a single target requirement of 15k DPS, 20k for vCoA2, 30k for vFH, high AoE and moving target scores for vDC2 etc. Put low healing requirements on vFG1, but high on vDC2, and same with tanks depending on how hard the stuff hits in the corresponding dungeons (low in vFG1, somewhat higher for vet Selene's Web, and really high in vMHK and vFL).
Once that is done, add a drop-down menu to the dungeon finder with options:
1. Run only with qualified people.
2. Only run dungeons I'm qualified for, but it's ok if some other people are not qualified.
3. A completely unqualified group is ok. (for those who want the current PUG experience or refuse/haven't gotten around to doing the proving grounds)
I'm sure it can be worded better, but this should be the essence of it. Based on the option you pick, your scores in the proving grounds, the role(s) you have selected (yes, please bring back multi-role queuing, my magplar did vSP hm both as tank and DD, I really can do both on the same char), and the difficulty rating of the dungeons, you then get put in the dungeons with people of qualifications you agreed to have with you.
The only downside to this would be that in the background the dungeon finder would need much more robust algorithms to sort all of this information to create fitting groups in optimal time, but the upside would be that real tanks can then be fairly certain that the DDs they are matched with are at least qualified for the content (even if they have to learn the specific mechanics). This would bring queue times for the different roles closer together so that there is less incentive for people to queue as fakes, on top of excluding fakes when you select the option for strict qualification requirement. This would also add content to the game, and make the Undaunted more than a place to get dailies, but also a place to prove your skills.
The proving grounds score should also override the CP requirement for certain dungeons, if it is high enough. That way an experienced player who switched platforms and has 180CP wouldn't be penalized any more, unlike under the current system. This is a rather minor point, but the fairer the better.
Now sure, people could get the qualification and then deconstruct the gear they used for it, but I don't see anyone who is good enough to get qualification for the last 2-3 DLC dungeon packs just ditching all the gear they used for it and then queuing as a fake, they will be people who are experienced enough to know how annoying fakes can be, and will at least have the decency to slot a taunt if they queue as a fake tank...
EDIT:
Solutions that fit the bill that were proposed by other people:
c) (Suggested by
@temjiu ) Increase the standard group size to 5 or 6 so that more DDs get in for each tank and healer that queued.