TPM, I think your post and analysis is well thought through and very important. As an illustration, on the West Coast, the only school that recruits nationally is Stanford...for obvious reasons.
The other major programs including Washington, Oregon St., UCLA, USC, Cal,Fullerton, USD, Loyola, etc are almost exclusively in state. USC has an occasional exception like Jeff Clement but mostly they recruit from LA/San Diego areas. I have my own thoughts on the reasons but I think these roster trends are quite well established and are not likely to change. I am not sure if it is true but I was told one of the UC schools wanted to recruit out of state and they had to get approval by the athletic department and others in the University to do so.
So, if you are out of state and wanting to play in the Pac10, WCC, or BigWest, you better be very good or be looking at Arizona State or Arizona, which also do a lot of recruiting in CA.