the most important aspect of PvE is that players know the content. It's not that important that players are super skilled at their class. Mediocre players beat 14s. What is important is that you interrupt the important casts, that you dodge the important abilities and that you don't buttpull left and right because you're running the route for the first time and don't know what you're doing.
My worst healing experience is when the tank doesn't have a high rio alt and just breaks into 10s. The routes are completely wild and unprepared. I had good runs end in a depleted key because the route was so awful that Pride spawned in the worst possible situation (ToP last small platform before Kul'tharok Pride spawn right when one of the smaller mobs died, for example.