Axe/Torch Trap Ranger (WvW zerg build)
I recently got my ranger to level 80 and geared him in mostly the precision/toughness/condition dmg gear from the karma vendors in Orr. Mostly all that I do with him is WvW and I find that a trap ranger is actually quite effective in a zerg if used properly. I run shortbow as main weapon and axe/warhorn for the warhorn 5 ability to grant swiftness to the zerg and as a blast finisher as well. From my experience using this build, I find flanking a zerg that is defending a camp or trying to attack a keep is the best strategy. Run into the zerg, use entangle, throw all of your traps, then run like hell to safety and then come back with shortbow to apply more conditions. That is usually enough to disrupt the zerg’s momentum enough for your forces to rally and push them back.
My only problem that I could see with your build, at least in the link provided, was that in the Wilderness Survival Trait line I see that you reduce the cooldown of Survival Skills when you use all traps. I would just suggest changing that to Vigorous Renewal or possibly one of the other traits depending on your play style.