http://www.mmorpg.com/gamelist.cfm/game/821/feature/8237/Elder-Scrolls-Online-Brian-Wheeler-Talks-PvP-and-Darkness-Falls.html
Alot of good information from Brian Wheeler
On thing really stands out for me. Killing a level 50 player solo will give better rewards than seiging an enemy keep.
No keep trading, objective hopping or circling. its about defending what you have, especially your home territory because you need all Your home keeps for any bonuses to take effect in Cyrodiil. Also you just make mch more rewards defending and killing enemy players
Also the balance mechanic to promote the lesser 2 alliances to attack the larger stronger alliance.
many purposes of groups roaming and doing hit and runs. they can have a huge -$ effect on enemy alliances by destroying keep walls and moving on. they can also nuetralize enemy zerg travel by cutting ports to keep by taking the resource places.
Melee has a alot more jobs to do in keep seiges than you think. enemies can sneak up to your seige and set it on fire, the operators need melee to protect them.