I believe that @adbono would be best t answer this question, but here's what I saw in 2016. When there were exceptional players on the field, both pro and D1 scouts were in the stands. I'm assuming that other colleges were there at times, but didn't have bling to announce themselves.
The coach clearly had ties to Texas Tech, Louisiana Lafayette, Tarleton State and a couple others because that's where a majority of the players went. However, my son went to Arkansas and another kid went to Oklahoma - my son was also drafted but didn't sign. So I think there's visibility and you go where your ability projects, but I don't think that players or parents reach out to schools, it's just the coach - @adbono would no better how this part of the process works,