imo the difference between blood bath and the other skills is that the effect of blood bath lasts forever... and that it stacks! If the effect was like "bleeding: 3 rounds" would it be so fearsome?
Nate must be gathering the statistics of Slayer battles over a reasonable sample population. If at all it needs to be balanced hopefully he'll do so in next patch.
But right now I'm eager to get that one perfect Slayer in my squad