So you are saying that there are not 13 Neb kids in the NFL right now. I found this: http://www.pro-football-reference.com/friv/birthplaces.cgi?state=NEThe problem is that people want to use those numbers as a reason to recruit Nebraska more heavily. Those 13 players are spread out over what 10 years or more years.
I think Nebraska has to get all the D1 players in the state, which they haven't done in the past 15 years. However, I don't think there is enough talent in state to devote significantly more resources on getting those players. Hell most of the time if you ask, they will come to Lincoln.
Oddly enough, there are 10 players listed, which is what would be expected.