Their hp values are fine, people just suck at their jobs and die too much, and dps is abysmally low as a result.
Keep in mind your average alliance roul party member is probably someone like this guy:
Fun story btw, they were in uldah shout the other week complaining about this exact topic. When nobody agreed with them, they got insanely pa about it and started lauding their forced ct queues over everyone there, telling people to cope if they wanted higher lv content. Then they got dogpiled and eventually stopped responding. Was funny as fuck.
But yeah get a competent group and the bosses melt.
