I think it is very difficult to generalize on competitiveness. Population of the state as a competitive indicator is a little misleading though I agree that it does impact ability to get a Senator's nom. However, congressional districts are sized roughly based on population - in NY the average district is about 700k people (in 27 districts). In Montana, it has 1 district of 1 mm people.
Also, many districts in big cities are not competitive - in our district (750k people) there were 5 candidates interviewing with our rep for all of the academies (3 Navy, 1 AF, 1 MM). I would interpret that as a virtual 100% probability of getting a nom unless a candidate has a clear deficiency of some type. I understand that LA, SF and Chicago have similar dynamics. At least 2 things are at play here - 1.) many underperforming urban public schools with no advocates guiding kids toward the academies and 2.) Many private schools and high achieving public schools with 95+ of kids who go to college after graduation and who are focused on 'name brand' public or private universities only.
It would be interesting to see a breakdown by state over time and also who is taken off of the NWL by state.
Just my thoughts on this, anyway.