Neither Anna nor Elena D. is the best -- or even 2nd-best -- Russian player on Tour now. I am talking about the whole package; not just raw talent, but the abiliity to use the raw talent to win.
Elena D. can win a small tournament next year (but only if she enters one that Anna does not also enter). But Elena prefers to enter larger tournaments for the most part. And there are quite a few players who are better than she is these days, so she is not going to snag one of those.
But it is a bit unfair to compare the number of finals they have each appeared in and use that as a gauge. Anna has played in 30 - 40 more tournaments than Elena has. Elena turned pro much later, and right in the improved-Venus-Serena era.