World War One, all over again

Ever since 2.3, there have been some major changes to Alterac Valley.
These changes, I think, were supposed to make it more strategical, and try to end the endless zerg rushing of pre-2.3 AV.

The very first iteration of AV was a monstrosity, filled with random NPCs, and even a random rampaging Troll. It has undergone many, many changes, streamlining the battleground into a PvP battleground again.
However, it is one that requires a great deal of execution compared to the Old AVs.

Pre 2.3, you got honor when you killed stuff. Thats it. So everybody bum-rushed everyone else, got tons of honor, and churned out thousands of honor.

Now, things are different. Do you still get honor from killing stuff? Damn right you do. 62 honor for killing the Captain, destroying a tower or bunker. You also snag a hefty 83 honor from killing the end general.
!BUT!
At the end of the game, your team is awarded 41 honor for having intact towers, and a living Captain.
So you lose honor when a Tower is capped from your side. You lose honor when Balinda/Galv get killed.
Furthermore, when one of your towers is capped, you lose 75 reinforcements. And when a captain dies, there goes 100 reinforcements.

In essence, the new AV requires a solid defence now in addition to a powerful offence.
If everyone from your team zergs forward, you lose honor when Alliance kills your stuff. But, if no one goes on offence, then you don't get any honor from killing stuff.

The old Horde adage was "Defence is for pussies". The whole horde mentality was one of simply swarming whatever needed to be done. In AB, for example, nobody would defend Lumbermill, because if alliance capped it, horde would simply zerg it back. I participated in this many, many times while leveling up, and witnessed 5-caps at 29, 39, 49, 59, and 69.
In warsong, traditionally horde would not have anybody on defence, and simply attack the alliance. Any defence the alliance had (which was generally 4-8 people) were simply steamrolled, and we killed the alliance flag carrier on our way back. That was how warsong was played. Alliance would put up defence, horde would annihilate defence, horde would win.
Over and over again.
Pre-70, thats how the game is played. I cannot say this is true everywhere, but on Stormstrike, if horde ever devoted more than 10% of its avaliable resources to defence, we would lose. Guaranteed.

But times, they did a-change.

And now AV is unfriendly to pure offence strategies.

So. You need to have some folk on defence, and they better be some damn solid folk.
Don't misunderstand this. You do not win an AV by having Defence. You delay your opponents victory through defence.
All defence serves to do is slow down and hinder the enemies attack, while your own offence pushes through to ultimate victory. At absolute maximum, half the raid group will be on defence. ABSOLUTE MAX. You need a minimum of 20 people on offence if you expect to be victorious in any kind of timely manner.
So, where do we devide who goes on defence, and who goes on offence?
First off, the people on offence will be fighting a lot of NPC's, while those on defence almost never will, and will almost exclusively be fighting other players.
Thus, people with PvE builds and gear should go on offence right off the bat, and those with PvP builds and gear are better suited to playing on defence.
Second, there are some very nice talents/abilities that lend themselves specifically to a role in AV. Rogues, for example, have been longstanding examples of excellent Tower-cappers. If you can "Ninja" a graveyard or Tower, you are an incredible asset to a team.
Any and all AoE fears are incredibly useful on defence. Priests and warlocks can ruthlessly upset the offence of the opposing team. In the same regard, a Druid's Cyclone ability can be devastating if you cyclone the main tank of the other team.

You get the idea.

So where do we stand, as mages?

If you're in Karazhan gear, play offence. You have better PvE skills, and will be far more useful to an effective offence.
If you're sporting S2 arena gear, you're better off on defence, as you'll be more suited to the heavy PvP combat that comes from playing that side.

And now to specs.

If you're arcane, you are very well suited to playing on Offence. Solid DPS and raid power, coupled with the brief PvP potential from those 3 minute mage abilities, will make you perfectly suited to playing Offence. When your offence runs into the enemies defence, you can pop those powerful abilties to steamroll them, and get right back on to killing Archers/whatever.

Fire spec is kindof a tossup. In general, you're better of on Offence, putting those handy damage abilities to good use. However, abilities like Dragon's Breath are incredibly potent, and can seriously shut down the offence of an enemy. A 3 second AoE stun is ridiculously powerful. Use it wisely, you can make a huge dent in, for example, enemy healers. Dragon's Breath can also be used on offence, and, indeed, Blastwave + Dragon's Breath can often single-handedly break a stalemate. The sheer amount of devastating damage seriously weakens your opponents, allowing your teammates to take them down quickly.
You will often die rather shortly after unleashing Blastwave/Dragon's Breath on a collection of alliance/horde, however.

Frost is an amazing defence build. No if's or but's about it. Slows, roots, what's not to like? You can frustrate any advance easily. The whole makeup of frost is mastery of kiting, and doing massive damage while the enemy is rather strictly controlled. In essence, it is perfect for defence. And if some brilliant people are defending with you, you can be unstoppable.
In old AV, I've witnessed 3 frost mages and a pair of warlocks stall the entire alliance offence for a good 45 minutes. Endless roots and fears kept them at bay for a very long time.

TL;DR version: play to your spec and gear. Prot warrior with 19k hitpoints? Go on offence and help tank stuff. Shadow Priest with 12k hitpoints and 500 resilience? Go on defence, and be the shade that wouldn't die. Resto shaman in Tier 5, with mp5 so high it makes Holy Priests cry? Go on offence, and spam chain heal. Resto druid sporting S3 gear? Stay on defence, you will piss a lot of people off.

And if you find yourself in one of those stalemate AVs, where the whole fight is essentially btoh sides rezzing and killing each other every 30 seconds?
I feel for you.
Attrition battles in the new AV really, really suck.