The overlap of capabilities is between StackStorm and Salt --
the later has many orchestration capabilities. For event driven ops it can even be used alone. I don't want to say that one is better than the other, but this comparison does not surprise me at all.
As a friend (big Ansible fan otherwise) would say: "Ansible is just a glorified bash script; nothing more, nothing else". Without making it a bad product, Ansible is that one limited to CM only.