Now 3/4 of the population has 405+ iLvL and ragnaros mount because of the bugs that made the bosses a real joke, if ragnaros would have been working as it was before moltdown not even 10% of the server population could defeat him, heroic DS was a pretty decent challenge but with it's major bugs that made it easier (mages and rogues doing milions dpd/hundreds of K dps, broken bosses that are easier and a lot of other exploits/bugs). Before moltdown, having ragnaros title/mount was something very nice, or having some hc DS pieces, or dragonslayer title for beating sinestra...now everybody has those, even the last noob, and even if they fix all now, people could still farm the content with their 405 mains and alts because with that gear it's way more easier. Probably a character wipe and a decent scripted content (at least lvl 85 dungeons&raids&chars) would help. As for pvp, just dont allow people to join arenas/bgs with DS gear and it will be fine imo (sorry if bad english)