Maybe it's because there's a part of me that's still a homer, but I still see growth and improvement in Byfield's game for the most part.
In Juniors, even before the draft when I first saw him, he was clearly one of the best players on the ice. And it wasn't just because he was bigger than the rest of the competition (although, sure, that played a part). But he was also a very fast skater for his size, even relative to his smaller peers. He has good hands. His shot could develop some work, obviously, but he can control the puck well in tight.
The knocks of "only scores off the rush" has been a pretty silly criticism, because most of the goals scored in junior, when I watch, are either on a rushing attack or with the man advantage. You generally don't see a whole lot of 5-on-5 cycles. The teams are either so close to each other that a cycle doesn't last, or the teams are so far apart that it's a shooting gallery against the weaker team. I invite you all to watch some junior games and tell me you see it differently.
Because of juniors, he did pick up some bad habits. Most commonly is the "fly-by" where he would approach a player with the puck, use his reach to poke the puck away and use his speed to lead an attack. Unfortunately, that doesn't work too often in the NHL, and he had to learn that. And more recently (towards the end of last season as well as the start of this season), he has deviated away from those habits and is starting to get more physically engaged.
To me, there are different aspects of hockey IQ - instincts and learning. And to make a comparison, I see Byfield and Fiala on opposite ends of the spectrum. Fiala has fantastic instincts which assist with his positioning and being in the right place. He knows how to use his skillset without hesitation, which allows him to play incredibly quickly. But you see him make the same kinds of mistakes again and again. No-look backhand passes where nobody is, and not even a good "area" to pass to; he takes those undisciplined penalties. This doesn't make him a bad player - but a flawed one, as all are.
With Byfield, he doesn't have the same instincts when on the ice. His positioning is off, where he doesn't go to the places he should. He still is learning how to use his body to play physically, which is why he looks timid. He doesn't sense a change in possession so he can make a break for a teammate to make a breakout pass for a breakaway. These skills he had used in junior have to be used differently, and it's just not a natural progression for him.
I can't provide a timeline to say how long it will take him to "learn" because frankly, he may not learn fast enough or at all - but I think his hockey IQ is being minimized here out of frustration with his performance. But there are elements to his game which have evolved. Reducing the fly-bys for one. He's looking around more, which affords him to move the puck quicker. But he still needs to learn puck placement not just with his shot selection, but with short passes, and he needs to learn to operate better under pressure.