I am primarily a TPvPer and I have just recently began playing WvWvW when my team isn’t online. In general I prefer small scale PvP, and in games like DAOC or Shadowbane I was often part of a group that would harass zergs on their outskirts and try to break it apart. When attempting this in Guildwars 2 I noticed several mechanics which favor the large zergs over small groups of players.
One of the reasons picking on the outskirts of zergs is effective in other games is because zergs tend to be less organized than smaller groups and have slower response times to a member being picked off or harassed in their back lines, especially when in transit between two areas.
So why is this strategy not as effective in GW2? The primary issue is the difference between in-combat movement speed and out of combat movement speed. If your group attacks the tail end of a zerg, say 2 stragglers at the back of a group of 30, maybe 5-10seconds behind the main pack. Even if you were to kill the 2 stragglers in under 10 seconds, and it took the zerg 10-15 seconds to realize what was happening, your team would easily be chased down by the group of people running at out of combat speed. If even one of the stragglers is on voice comm, improving the response time of the zerg, it becomes impossible to escape. There is no possibility of successfully disengaging from a fight with a zerg.
In addition to the factors which make it extremely difficult to bring down stragglers in a zerg, the game mechanics make it so that there is no impact on the zerg for allowing those players to die. Even if your small group, downs and stomps the straggler, the entire zerg can come back, and if they choose to not run you down with their massive out of combat speed advantage, they can simply revive their teammates corpses and carry on.
The final mechanic which promotes zerging is simply map design. Everything is too confined and cramped together. Besides simply killing a zerg, another way to effectively "defeat"them, is to waste their time by attracting its attention and bringing them on a huge chase out of the way of their objective. The current maps do not allow for this at all and within a minute, or two at most, you will find yourself facing some walls.
I do not know the best way to alleviate these issues, I have a couple ideas but I do not think they are the best fix, just maybe the way to get the ball rolling on some ideas. I feel like there are two approaches that can be taken, either give incentives to the small group players, or give disincentives to the zergs.
I think all the incentives/disincentives should be based around mitigating the game mechanic bonus zergs have. My first idea is a debuff for the zerg, when a certain of number of allied players are in a relatively close proximity to one another, they receive a debuff. I would envision this debuff as something that either tied their combat status completely together or one which provided an across the board movement speed decrease. Zergs would keep their power but they would become slow moving armies in comparison to the agile, smaller guerrilla groups. If the route of incentives for the small groups were chosen I think they should receive a buff that increases movement speed and allow for their stomps to send people back to spawn unable to be revived at the point of their death.
Maybe I am off base here and these changes aren’t needed at all but it seems like everyone I have spoke to is a little off-put by the amount of zerging in WvWvW and I think the zerging is so prevalent because of map design and game mechanics (hi 5 max target AEs). Zergs have a inherent advantage simply due to their sheer numbers, providing these extra incentives seems excessive.
TL;DR : Make zergs slower or small groups faster
