Their D core outside of OEL and Goligoski is pretty weak.
I wouldn't say their D is on par with ours, so I'm not sure the statement about Juolevi is true. He would have had to beat out Edler, Hutton, Sbisa, and Tryamkin. Chychrun didn't have nearly the same level of competition.
Under Tippett's system any average goalie can look good, so I'm not so sure it's not just lack of depth on D. Regardless, unless a D-man is on the same level as Ekblad they shouldn't be playing in the NHL at 18.