You got your seasons mixed up son.
S5 pally (ret and retholy), dk, arcane mages, surv huntards
S6 pally (protholy), dk, brostorming warriors, prot warriors, beastcleave
S7 destro, ele - imo most balanced season up to the date
S8 locks, restodruids, ele, wizards everywhere
S9 dk, feral, restoshamans, priests being unuasable in arena (before 4.O6), few major patches during season, warrior damage, mmr exploiting...
Yes the balance used to be a lot worse.
S5 - hpal/dk/survival/arcane/ret/protholy
S6 - frost dk, beast cleave begins, ele, destro, PHD, TSG
S7 early - beast cleave, ele, destro, PHD, turtle cleave begins
S7 post-resil - dot class rise to power due to huge relative damage buff of resil change, turtle cleave running rampant
S8 - wizards everywhere, protret/rsham/disc
I guess you can toss dispel cleave and LSD on a few of the seasons, and definitely MLD on season 8. Instant cyclone came in to the game around S7 and brought ferals to a few t2 comps.
Honestly though, cata pretty much shit on too much about the game class balance and ability wise. Unless you were a resto druid even S5 is looking awfully tempting right now. Even with nitro boosts, TNT stun, "did they even think about this" level death knights, and that dumb burst trinket.
Edited by Watlok, 08 September 2011 - 08:31 PM.