I agree JEV would perform similarly to Dan in RBR, but what they are looking for is Sebastian II - a teen phenom that does something extraordinary in the lower formula like outscores his teammate by 8 times or wins a GP or whatever - apparently. I am unsure why they are taking that approach. Alguersauri and Buemi would have also done well in a top team, imo, but I suppose that is not enough; they want a star in STRF that makes everyone sit up and take notice. Kvyat is doing that, but not to the degree Seb did yet. However, I think the kid is capable of kicking up a storm, so let's see. Meanwhile, next season will be tricky for Daniil and Max in that regard, especially if a seat is opening at Red Bull.
I didn't say JEV "would perform similarly to Dan in RBR". He wouldn't. He might be a step up on Vettel's performance so far this year though, so in that respect he could be a Seb "Mk II", - a better, improved version of the original.
IMO...