The above is a 22 year old prospect with four years pro experience. For each particular rating, you can see the progression from season to season.
For example, look at range. He improved 5 points from S22 to S23, another 3 points from S23 to S24, and 1 more point from S24 to S25. Assuming he's had pretty consistent coaching and playing time over those seasons (as well as a consistent training budget, as range is a "physical" rating), and will continue to have similar coaching and PT going forward, it's safe to say that his range is pretty much done progressing. Maybe one more point at best.
A second rating to look at might be glove. He progressed 11 points, then 7 points, then 6 points. Assuming similar progressin, he might have a couple more seasons where he progresses 4, then 3, then 2 and maybe 1 before he stops. So you're probably looking at a final glove rating of around 90.
Repeat this process for all key ratings. You can pretty much determine what his final peak is going to be across all ratings without ever knowing what the projected ratings that you would get from ADV are.
Granted, this prospect is a little easier to project because he has four seasons of progressions that you can track and project forward. It's much harder for a second year guy because you have much less data to work with, and near impossible for a first year guy because all you have is his starting ratings.