I mean all those players played when scouting consisted of old smelly guys smoking cigars, drinking scotch and taking a couple of drunken notes. Modern scouting can’t be compared. That being said, 10% of 4th rounders make the show. Higher than I thought but still pretty low odds.
https://dobberprospects.com/2020/05/16/nhl-draft-pick-probabilities/amp/