I have to say that I agree with this post pretty much. To me Rantanen has been a pretty much overrated Finnish prospect. A bit in the similar way as Barkov to some extent. Don't take me wrong though, as both are magnificent prospects, and I definitely do see Barkov as one of the players in the best tier of the young and promising Finnish players. And Rantanen is definitely a tier lower, although a good prospect definitely too. But I don't see him very special still. He has size and pretty good hockey IQ, but he has pretty abysmal shot for that size of a player and he also lacks way too much drive and a killer instinct in his game.
It's a bit hard to explain, but some players have this real killer instinct, and from the best Finnish prospects I see that Laine, Aho and most probably Puljujärvi have it. Barkov seems to lack some of it in a similar way that Rantanen does, but Barkov compensates it still with his very complete and high skillset in general.
I just really don't see that Rantanen will ever become a player that will score at least more than about 50 points in the NHL. But of course that would already mean that he would be a pretty darn good NHL player, if he would ever get 50 points.