I do a lot of M+ groups. One thing I've started to noticed is that when people are invited from certain servers, regardless of their ilvl and perceived experience, they are just bad. e.g. Have strange, inefficient, and often deadly dungeon routes; never interrupt casts; low dps despite high ilvl; and generally lead the group to their death multiple times. Ever see this? Is this a latency thing based on server location? Cultural? Language?