Early game tanking and flashpoints are whatever, but I can tell you as a tank at level 50 in HM flashpoints if your tank is trying or even succeeding at holding threat on every mob in every pack he is doing it wrong. Due to the nature of stuns, ministuns, and the way normal mobs do almost as much damage as strong and elite mobs but die so fast, by far the easiest way for a group to handle things, on both the healer and the tank, is for the tank to just focus on holding agro on strong and elite mobs, and the DPS should be handling normal mobs first, taking their agro themselves, and killing them before they can do any significant damage. Even strong mobs should be able to easily be soloed by a decent DPS before much damage is done, with appropriate use of stuns, interrupts, etc. The tank has 2 major tasks, making sure very mob is at least tagged (mobs on the healer is the only big threat taboo really) and holding agro over the elites, and strongs if possible. As long as you were targetting the mobs in the order of weakest to strongest, you were doing it right, taking some agro, if you were pulling agro on strongs and elites while the tank was focusing on normals after having tagged the other mobs, well then it was your fault.