With between 400 and 500 AV games played, I feel I can give you some decent advice. My way is always to try and 'failproof' the AV as much as possible.
Few scenario's:
1. If you attack, you can only defend 1 assaulted bunker, so you rely on the other teammates to cap the other 3. If they don't, you lose.
2. If you defend Galv and turtle it, the alliance will respawn and probably recap their bunkers which turns the game in a complete grindfest. You have 2 options here, either defend your towers or farm Alliance and hope other people defend. If they don't defend you lose. If they're failing at the grinding, you lose.
3. Join your raid to make sure Balinda dies and that the alliance raid moves into your base. You should now be able to recap 2 towers/bunkers and hopefully IW/FW GY's which gives the alliance a tough time at Drek. Thus buying your raid more time at capping the alliance base, which in most cases is needed since Alliance seems to rush south a lot quicker then horde rushes north(partially due to NPC's in the alliance base)

I always try to go with option 3. Your burst damage is most usefull since you need to wipe the alliance quickly in your towers to recap them. Defending 2 towers should be very doable. Where trying to assault 2 bunkers at once is not possible. You do need to feel comfortable inside buildings though and keep a close look on your slaves.

On the main team, 4 shamans I have 238 AV battles played, 157 won. Taking note of the ~50 battles I lost at lvl 60, that's quite a good win ratio if you ask me.