The academic research industrial complex, or whatever you to call it, organizes itself in some way. So the people who are working in areas that are instantly recognizable as not only good, but also friendly to the notions of the discipline are easier cells for people who do higher than people who work at the boundaries. Different disciplines have very different standards and ideas of what problems are interesting,. how much you should have published and all. All this kind of stuff is different because you have a whole bunch of informal customs and rules that grow up - not just formal bits of knowledge.