What are the "attributes" that you believe are needed to make the NHL Juolevi doesn't possess? He makes smart decisions with and without the puck and is 6'3 200lbs. He's a solid bet to make the NHL, even if he only ends up a #3 d-man.
No players "floor" is a number 3 d-man. Juolevi's floor is probably what he is now which is a decent SM-Liiga defender. Now, him being that is probably unlikely, but young defenders development is so erratic that its hard to call someones floor a number 3 defender. Just look at guys like Cam Barker, Bogosian, Schenn, Gudbranson, Ryan Murray, Griffin Reinhart, Jared Cowan, and Derrick Pouliot. Very few guys floor is that high. Young defenders have significant risk attached, and almost every player drafted outside of the uber-elite talents (such as Crosby, Tavares, Stamkos, McDavid, Eichel, MacKinnon, Doughty, Hedman, Eichel, Matthews, etc) is a non-NHLer. While unlikely, because like how very few people reach their perceived ceiling, very few underperform to the level of their floor.
I liked Juolevi in his draft year, he was smart and composed and used to be good at avoiding the forecheck. I didn't pay as close attention to the Knights last year, but he didn't progress and in some ways seemed to regress last year, and that was backed up when I talked to people who avidly watched the team (a general vibe was Mete was outplaying him).
Good for Juolevi bouncing back and doing well in Finland, although, I would avoid reading too much into the whole "he's producing among the best rates for u-20 Finnish defenders in the last 30 years of the league" simply because how many legitimate number 1's have come out of that league in that time frame? The countries best NHL defenders of all time are Timonen and Numminen, who were good defenders but never really Norris candidates, and the only highly hyped guys based out of there were Aki Berg, Pitkanen, and Risto, all of whom were out of that league by 19 (although Pitkanen did play his 19-year-old season there). Good for Canucks fans that he looks back on track, and is on the verge of putting himself again in the discussion of a top 10 player from 2016.