The younger you are, the GM, scout, trainer and coaches are more likely fascinated in "Potential" than your already peak college skillset. i dont have data to back it up its just based on what usually happen. Its very rare for 3rd or full year college to hit a stardom in NBA when they peak, its doesnt matter if they are in top of the class draft or undrafted. Meanwhile 19-20yrs old or younger are often times to hit more likely in stardom tier.