I've been doing the national rankings for a long time, and one thing I've noticed is that talent runs in cycles -- one year there's a lot of talent in Texas, and the next year, Georgia is loaded. Southern California, over the years, has produced many D-1 players, but recently has been going through a bit of a dry spell, and NorCal isn't as strong right now as it was five or ten years ago.
All that said, Nike wants to maintain programs in certain areas, and it makes sense for them to do so even when the talent cycle is down in those areas -- thus teams that don't do as well. And also, the EYBL teams have to have a certain level of organization and professionalism, not to mention experience in dealing with Nike, so there's a kind of inertia that keeps the same teams in that league. Of course, changes are made, but from Nike's point of view, Southern California, for example, is a huge market for their products, and could well bounce back talent-wise within the next five years, say. So rather than cut teams now and add them back later, it appears they prefer to just ride out the talent cycles and keep the same organizations they are familiar with in the EYBL.