I was watching SSL1, Ro16, Hero vs.Barracks. There was a moment when Barracks got a group of marines on the high ground and started shooting Hero's Evolution Chamber (picture below). Hero reacted by casting a dark swarm on that building covering it fully, yet that did not help as the ranged damage continued to apply until the Evolution Chamber was destroyed. SC has many bugs, some of which actually make the game more balanced in my opinion, but this definitely ain't one of them. Why is this happening? Is this really the case of ''shoot first'' and don't worry about ''dark swarm''? I have only noticed this phenomena on buildings, not units, but i might be wrong - correct me if. If zerg knows about this bug, why even bother casting a dark swarm on a structure that is doomed to splash and instead cast a spell elsewhere?
Can someone extrapolate on this matter?