Except, a premade gets to guarantee they get those 4 good players together in every game they play.
A PUG is playing the lottery, and very very likely to get screwed because the average player is not as good as a handpicked team of geared players with the right composition.
You missed the point of what I said, so lemme try again. This was in response to the person saying PuG's -couldn't- fight at the same level as a Premade in terms of coordination.
Good strategies rarely change, and those who know them can use them even without practicing with a particular other person.
Focus'ing a healer is common sense, as is getting them away from a tank. If the fight is 4 of you to 2 of them, it should be pretty easy to guess where the other 6 are. Likewise, if you go to break from the fightt head to were those 6 are and someone else does so too, it shouldn't take words for one of you to decide to let the other go, and keep this fight 3 vs 2. Perhaps one of the more common problems is mezzing. You shouldn't need to communicate not to break someone's mezz. At the same time, you should know not to mezz if it is likely to be broken (aka, in the heat of a fight with aoe).
So yes, a Premade is more likely to get 4 good players (though there -are- bad premades) from fight to fight, but it is nonsense to say a PuG can not act with the same level of coordination and strategy as a good Premade, if the PuG's are actually good players.