I'll share my experience - for what it is worth. A few years after my son graduated high school and was off playing college ball, I went to see a game at his old high school which was in a rural part of California.
There was a kid there playing shortstop who was, in my eyes, a college prospect - good range, very strong arm, fast, and hit with authority. I talked with his dad and he mentioned that his son had not played any summer ball nor had he attended any showcase type events, nor played any travel ball. He went from HS baseball straight into football workouts. He was the starting QB on the football team and the starting point guard on the basketball team and was in the spring of his Junior year.
So I was pretty sure that this kid had not been seen - and I checked the PG lists. Nope, not there. I sent Jerry Ford an email as he and I had traded a few messages over the years. I suggested that he have someone check this kid out. Jerry said he would call a friend who lived nearby and have him call me. I got a call a few hours later. We agreed to go watch a game together and did so a week or two later.
Two weeks after that, the kid was in the top 1000. He signed with a Pac-12 team, played 4 years and is now working in baseball as a scout.
So basically on a tip from someone they knew (me) and one peek from a baseball guy they sent out to follow up on that tip, the kid from nowheresville ended up on the PG list.