I think focusing too much on any particular draft slot is probably not as instructive as looking at the range of picks around it but the point you are making is a good one to help set expectations.  Here are a couple of studies on value by slot that reinforce the amount of failure that comes with the handful of big successes like Jameer Nelson and Big Z: https://tonyelhabr.github.io/nba-decision_analysis/what-research-says-about-nba-draft-pick-value.html