Why PUG groups fail - World of Warcraft

I seem to be all about revelations these days. This one occurred as I was fleeing the icy grasp of the Lich King in the Halls of Reflection. The gist of this revelation was..."we're going to die". It wasn't a lack of skill in the group, or at least I don't think so. It was something different, and I think it might be why pug groups fail.

The Sense
It's kinda like the sixth sense only you don't see dead people. We'll I suppose you do, everyone in HoR is dead. Anyway, thats beside the point. This is something different entirely. I generally play with a core group of people, and I would say thats typical of most. And out of that core group there are really only two healers that run with me. I know those healers well, I've been playing with them since about level 19. I know that when healing is going well my health hovers, it may not be constant but it hovers, dipping only occasionally. Because of this, I generally know when things aren't going well and can adjust my tanking by changing seals and judgments to accommodate. And when things are really going bad, I can burn cooldowns like divine protection or lay on hands, however, they are my last resort.

Here's where pug groups fail. I don't know the healer from Adam. My health may vary from 25% up to 90%, its not constant, and I can't tell if he/she is having a hard time or just prefers to pop big heals. So my sense fails at the second to last stop in HoR. Health is down to 5-10% I no longer trust that its just play style...and cooldowns and trinkets are popped. We live through this battle, but it may have cost us the war. We're now backed against the last barrier, the hardest barrier, and I can't save myself if needed. There is too much damage to bad had....wipe.

There is an unexplainable teamwork that goes with people you normally play with, a sense that when things go wrong you know how to help the other out.