I'll take the 4 on the bottom
This is a noble statement, but it got me thinking, who are those guys.
They are
Duke QB Daniel Jones
Josh Allen, Kentucky
Tytus Howard, Alabama State
Marquise Brown, Oklahoma
Jones' story is interesting. Private school kid in Charlotte, basically missed his whole post junior year recruiting cycle. Still surprised no on picked him up. Duke had to greyshirt him. Also might not be first-rounder good, but that's another matter.
Allen came in undersized, but also probably underrated. He'd been a receiver through his junior year, and not a fast one. He transferred his last year and was moved to defense, but still probably should've been rated better.
Howard gained 80 pounds in college after coming in as a tall, 230-pount TE. He was part of a 4-7 team that averaged 14.7 points a game, so he might well be a workout warrior.
Brown is sort of cheating. He came out of HS either at 130 or 140 pounds with enough grad issues he couldn't enroll at Utah State. He was a four-star out of JUCO.
So mostly these are small players, projects, whose bodies allowed them to become better (or they were simultaneously underrated but also overdrafted in the QB's case)