That's the whole catch, you're picking kids before they show talent, that's a total crapshoot. The vast majority of them won't be late bloomers, they just continue to suck. If there was an easy way to figure out a late bloomer, guys like Gourde (or even Backhand Luke) wouldn't go undrafted.
A lot of times, late bloomers tend to get picked the year after though, like Mazur. Comments on the pick are funny in hindsight, lol:
Carter Mazur (LW) 6'0 / 168 lbs Tri-City Storm, USHL Heading to the University of Denver for 2021-2022 Profile: Carter Mazur at eliteprospects.com
forums.hfboards.com
Anyways, you're basically saying teams should hindsight draft. Yeah, that would be easy for sure, lol.