I would say that most of the successful players into or during HS years can feel like a straight line but it really depends on what is being evaluated. If my son had remained at the lowest level (AA), his performance would definitely make it seem like he was a top prospect compared to the players at that level, and possibly into HS. But as he advanced each level, there was a re-evaluation and focus on certain things to improve on because each step up through AAA to majors was challenging. It exposed him to more talented players and better play and to his own weaknesses and strengths, which made his path curve. I would suspect there are some rare players born with the talent to be a rock star player at 8u and still be that much better than everyone else through 18u.