So often I find peope like to place blame without fully understanding, awesome your making the effort. Tanks need to be the first to tag any enemies, casters and ranged all to often will tag an enemy with a dot before tank is even close enough to flash. If this happens it is near impossible for tank to regain agro. Often tankwill be blamed when it was the dps healer. Also dps needs to back tank (except in special instances boss fight dynamics. This is where markers can come in handy for a team who has trouble getting together on a single enemy (the one tank decided to go for 1st)