You asked what would a better Dman that couldn't bolt to Russia get. Sergachev is good but unproven and they had to add a conditional 2nd to get Drouin. A proven Sergachev with no risk of leaving would have got Drouin straight up.
Meaning a better Dman with no risk of leaving for Russia would fetch one of the best young forwards in the league, straight up. On the other hand, a 25 year old Dman with very few points that just missed almost a full season of hockey would not fetch the same thing, not even close.