Kallionkieli has a shooting percentage of 27.4%, which is unsustainable, though at 25.5%, Brink's shooting percentage presents a similar problem. Maybe scouts are waiting for one of Sioux City's big three to get injured for a stretch and see how the other two do without him. The other thing that may concern scouts is Kallionkieli's progression. Last year he was well-below a point per game, not in Finland's highest junior league, but in the B juniors( the top under-18 league), only playing a few games in the Nuorten SM-Liiga, and now he's putting up amazing numbers in the fourth-best junior league on the planet. That's some pretty rapid development over the course of the summer. I don't think I've ever heard of anything quite like it. How much of it is due to playing with two very good players?
It's not unprecedented for a player to transition well from the Finnish B juniors league to North America. Aleksi Heponiemi did it in his first year in Swift Current. But unlike Kallionkieli, he dominated the B-juniors the year before, scoring at over twice the rate Kallionkieli did at the same age. Maybe scouts and ranking organizations are being cautious with Kallionkieli, waiting to see if he ever comes back down to earth.
All of the above isn't to say I agree with Kallionkieli being ranked as low as he is in many places, just some guesses as to the reasoning. Also, is there any indication about his plans for next year? You'd think that NCAA programs would be beating a path to his door at this point.