Originally Posted by
Lubricious
It's the end of the expansion, with a tier which is running way too long. This means most skilled players have long since stopped raiding anything below normal (if they are still raiding at all), unless they are on an alt that is undergeared (which will presumably move to normal before long). Also, the extra time for the casuals to catch up has given them now the opportunity to reach gear levels that suggest they are ready for flex. Unfortunately these people didn't even pay attention to the mechanics in LFR, let alone flex. So now they are expecting the same bad play they see in LFR to work for flex, and that almost always leads to blaming a tank that knows what they are doing.
I have two toons that tank. When you are doing LFR or flex, there is a roughly 50% chance that the other tank will either be bad at tanking, or just not know any of the fight mechanics. It makes tanking incredibly difficult. It's doubly frustrating when you have tanked normals on that toon, and people talk to you like you don't know the fights.
There's not much you can do except what you tried to do with that second group which you ran. Tell people before you queue it up that you know what you're doing, and that if anyone tries to give you a crap strat or whines in general, you'll just remove them from the group. Then it won't be a surprise when someone like that mage is immediately shown the door. You're still going to have to deal with morons showing up, because at this point flex is LFR 1.5. The addition of the extra upgrade slots really encouraged more people to start running flex that have no idea what to do in there.