I admit one of the first things I do when I show up for defense is repping the wall because if you are fighting a big zerg you are not killing that many players especially as a support and there are not enough siege weapons for everyone to (sometimes) get any participation. The whole participation calculation sucks! people rush (and fight) over killing npc’s in front of gates and on the wall and only after that start building siege that the commander has through a while ago in hope to somehow get silver participation. The problem is, that if there isn't an enemy zerg around, there is just not enough to kill to get Gold participation especially if you are in a group.
I say it again if you want to reward the big fights, make them scaled events or special events. If x amount of players fight against each other over an objective (or even in open field) the event scales or becomes a special event and then you get the really really good rewards. And for an unscaled event you still get your Gold participation and the good rewards if you manage to get in that circle, because there is not enough to kill and not enough siege to man to even get silver participation for a group of players.