I'll chime in even though the question wasn't directed at me. Some things I've noticed or deduced with the current state of WoW:

--> Resilience. This makes crit builds much less effective. Since Arcane/Fire mages rely on crits for a fair portion of their damage (dmg+ignite), this detracts from their desirability in arenas. Shammies can mitigate or redirect a lot of damage via totems and chain. Warlocks can mitigate a fair amount through soul link and CC/interrupts. Locks can also damage while moving and while out of LOS through DoTs. Much more in the way of options than with mages.

--> Stamina. With Outlands gear, it is common to see people with 10k+ hitpoints. This means you have to churn out quite a bit of damage to kill these people, especially with a healer spamming out 6k+ heals backing them up. Where before, you could hit most well-geared people with 4x PoM/Pyros and instagib them, you can't do that to someone with 12k+ HPs, especially if they have 200+ resilience. This again makes more survivable classes like locks/shammies more desirable.

--> +Healing. With Outlands gearing having healers with easily +1200 healing, you have a hard time just bursting someone down outright if the healers are on the ball. On the other hand, mages can stack enough damage quickly enough even with stamina/resilience to kill people before they can be healed if their healer is being interrupted/silenced/beaten on. This is one area where mages might be more desirable as they can counterspell/gib the healer and then go to work on the rest. As an example of non-mage classes not working so well, Oath and I chased a level 70 shaman all the way from TM to SS last night with him stopping to spam a heal every 5-6 seconds. We could not damage him fast enough with 8 CoAgony and 8 corruptions ticking away. The only way we killed him was with death coil interrupt, felguard intercept stun and/or felhunter spell-lock.

--> Pets. Warlock pets provide quite a bit of "unattended" utility in PVP and some ghetto tanking ability in PVE. Being able to interrupt/harass one person, have DoTs ticking on another person and focusing drain life/shadowbolts/fears/etc. on a third person means you're doing quite a lot at the same time. This is more than most PuG PVP groups can effectively deal with. Mages tend to be the unconfusing all-or-nothing version of this. Each approach has its benefits. :P

--> Movement. One of the best benefits IMO for warlocks is being able to drop DoTs on people while moving. Mages can do some damage with instants and AoE but this requires A) close range and B) lots of mana. Mage primary damage outside of the 3-minute PoM/Pyro requires you be standing still and facing the target. Warlocks can put out 75% of their damage without even stopping and on multiple targets at the same time.

--> Totems. Shammies have a totem for nature, fire, frost, ranged and melee resists. With 5 shammies, you can have all 5 of these down, making your group resistant to everything but shadow/arcane. 5x healing stream totems is like having a 2-minute renew on the whole group. Fire nova totem, assuming similar +dmg, is roughly equivalent to blast wave minus the daze and extra crit. Then stack on grounding totem, tremor totem and snare totem and you have a very robust set of group synergy just from totems. (Yes, some of these share the base totem type and can't be cast together, but with 5 shammies, you can cover most of the bases.)

--> Ankh/Soulstone. Warlocks and shammies both have wipe-prevention devices. Soulstone has a slight advantage in that it can be cast on other party members (like a priest/paladin/warrior).

--> Shammy healing. Shaman chain heal x5 means you'd have a very hard time killing them unless you kept them AoE feared.


I'm sure there's more and Ellay/Zin/Oath/Ebola can correct or add where needed.