I think the struggles that guys like Bemstrom and Ponomarev have had in the NHL after having great AHL seasons make me a bit more hesitant to predict NHL upside based on AHL stats. Both of those guys are having really strong AHL seasons but looked completely ineffective in the NHL.
I think the thing that needs to be looked at more is skillset, in that whether these guys have notable attributes that is causing them to have success in the AHL. Someone like Poulin is doing fairly well in the AHL, but I don't see anything in his game that really screams "NHL contributor". I'm really concerned Ponomarev falls in that category as well. On the other side of that, McGroarty's super high hockey IQ stands out and his all around game is great that I think he's an extremely safe bet to be at least a good 3rd line caliber player. I think Koivunen also has some noticeable traits with his skill and hands that make me think he's more likely to have success in the NHL.
The good thing with Broz is that I've really liked what I've seen from Broz when I've seen him, but I want to see more of him myself to get a better idea of what NHL traits he has. If he's just a generally good player without any notable traits, I'd be worried that his upside is capped as just a good AHLer/fringe NHLer. I'm also super interested in seeing Hayes, that stat line as a 21 year old is super impressive.