What's the probability that any given player selected in the NHL entry draft will be ranked in the annual Future Watch magazine released by the Hockey News? They rank the top 75 prospects in the whole league, then do a top 10 list for each team. Everybody who appears on the top 75 list will also appear on the top ten list for individual teams. The magazine excludes players who are currently playing in the NHL; so the rank represents the best prospects not playing in the big show that are owned by NHL teams.
The graph below shows the probabilities by pick for age 18, which will be the first season after being drafted. The blue line is being ranked in a team's top 10, and the orange line represents the top 75. Picks are bundled into groups of 10, with the dots representing the average for all the 10 picks preceding it, the continuous lines are just for visual effect.
A 1st round pick is almost 100% guaranteed to be ranked in his team's top 10 the season after being drafted. Players drafted from pick 20 to 30 will have a 60% chance of appearing on the top 75 list, while those drafted 30-40 will have a 20% chance. The evaluation system used by the Hockey News does show a clear preference for ranking 1st round picks in the top 75. If you looked at Expected Value metrics for NHL draft picks, there is not a huge difference between picks 20-30 and 30-40; but certainly looking at how the Hockey News values being a 1st round pick, there is a huge difference.
The graph for age 20 is similar to age 18, but with one key difference. If you are a top 20 draft pick and are not already in the NHL by age 20, your probability of getting ranked in the top 75 is significantly smaller than age 18. There's a proportion of the 1st round pick population that's already a bust by age 20, which is represented in the numbers. There are many high draft picks that are playing in the NCAA at age 20, and those players generally don't see their rankings drop unless they are exposed at the college level (like a Patrick White).
I love the Future Watch magazine and my heart always skips a beat when I see one on a news stand for the first time each year. I think they do a fantastic job of ranking prospects. My biggest complaint is the disparity between picks 20-30 and 30-40, that is larger in Future Watch than we observe in real life.