Now you're just being wrong or don't remember well. Unlike you said, Rantanen's process with the skating didn't start at the NHL but it had already begun in the FEL. During the season 2014-15 he was not only a good, but a great skater for his age. If we added in the size equation, I'd say he was elite. Had very little time so I just checked his highlight vid, which normally is pretty bad when you're looking for details. Skating is one aspect that leaves little room for questions however. So let me illustrate:
https://www.youtube.com/watch?v=uktW7vjfFQ0
See the clips at 4:55,
5:20, 8,50,
9,55, 11:40, 12:00. The underlined cuts are where he practically is flying past the defense. The others parts underline his overall skating - first steps, agility, balance and so forth. This was Rantanen between age of 17-18. I'm sure there's more and the vid didn't include the international games either. What's so unique about it all was the fact that just year before Rantanen was an average skater at best. So far I haven't seen anything alike from Kotkaniemi and I seriously doubt the fact that he has Rantanen's speed or overall mobility on the ice (in age to age comparison). That's not to say Jesperi isn't a good skater (especially what comes to agility & balance), but rather that they weren't at the same level which at the moment seems pretty obvious for those who've kept an eye on both. Kotkaniemi is far closer to young Barkov in that category than Rantanen.
I never understood your criticism about Rantanen and talking about him like he wasn't a grade A prospect anymore than when you elevating other young promising Finnish forwards into an entire different category. In general I've agreed about most things you've said, but in this case I think you got it wrong from the get go. Personally I never understood how it was possible for him to fall that low in the draft, because he had everything you'd want in a player, size, speed, IQ and elite tools. #8 was the latest I thought he might slip. Guess some teams hesitated about his goal scoring ability and viewed him more as a playmaking winger, but scoring doesn't seem to be a problem for the kid. An absolute steal for the Avs and I hope that Jesperi turns out the same (not to mention ending up as a center). I do see some Barkov in him as well.