When you actually build good defenses but the entire team doesn't use them and instead stands in front of them in the open, and then gets completely wiped out by Zulus. Or when they do use your defenses, but as soon as the Zulus get close they all retreat, pretty much meaning the defenses were useless. You're supposed to hold the walls, thats the point of walls, there's no point if you run away as soon as the enemy gets close, thats like leaving a city as soon as it's besieged.