Are we being too black and white about it though? Seems like we're saying that either a guy is very skilled at 18 or he sucks forever.
What about the (potential) development of these young players? Is there no option for young players to improve while they're outside the NHL?
I don't think it is black and white, nor that players can't improve. I would say that people seriously underrate the skill in the NHL overall. So many of these players are absurdly skilled. To get by on skill alone, we're talking the top .1% can do that. We frequently see guys who get by on their skill sets being humbled in the NHL. Byram is honestly a great example... he got by on simply being better than everyone else for his whole career prior to the NHL. He was BY FAR the most talented player on any team he played for up until the NHL and he played like it. He took over games for his team, did what he wanted when he wanted, could run his mouth to anybody and back it up. Now in the NHL, he's hard pressed to be a top 5 most talented guy on his team. Suddenly his game has to change. Instead of bending the game to his will, he has to fit into a role within the game. He's a more extreme example, but this happens with many guys.
Cogliano was an elite player through college, but when he got into the NHL, he couldn't dominate like he could. He had to change his game and find a role. And he did as a 3rd line, PK guy. Many guys struggle with that transition.
Every player can improve to a point, some end up limited by skills, style of play, frame, etc. When you get past the very elite skill guys, you get more into how they can fit in a NHL roster. Malinski is more skilled than a lot of NHL defensemen. He skates well, has a decent frame, and can attack offensively. But he's not more offensively skilled than guys like Makar, Toews, or G. So trying to make it as 1 of 6 every night defensemen, he has to find a niche. It won't be on a NHL power play, so he has to be a reliable PK guy and defensively without losing that offense. That's realistically not in his skill set.
A blast from the past name... Sheldon Dries. I don't think people actually realize how good of hockey player he is. He's a dominant AHL guy who makes players like Ivan and Foudy look bad. He can control the game at that level and looks far more skilled than them (same with guys like Tynan and Agozzino)... he just can't do enough in the NHL to make it work. The step is too large.
When people talk about any skill in a player's game whether it be a shot, hands, skating, etc... they don't really look at how much of a driver it is in the success at the current level and how that skill will be in the NHL. If that skill is minimized in the NHL where they trend more back to average... that player will have a hard time transitioning and have to find a new route to be as effective.