I still haven't had time to watch the rest of BRA-RUS, but for me, one main factor for Brazil's improvement is that Ze Roberto finally found his best roster and Ovchinnikov changed the system when Lyuba played.
In the first matches, Ze switched setters and OHs back and forth and it was bad for the team's rhythm and for the players' confidence. Now he finally decided to play with Garay and Dani, and it works well for them.
For Russia, Ovchinnikov could not simply interchange Estes and Sokolova, but when Sokolova played, it also meant Goncharova had to move to OH2, so it was almost like Russia having two different line-ups. Even though it looks like Lyuba did very well yesterday, I have the impression that Gamova and Goncharova played better with Estes in the team...
Another thing, QFs proved that preliminary results and rankings don't mean ANYTHING eventually. We have one 1st ranked, two 3rd ranked and even one 4th ranked team in semis while one 1st ranked and both 2nd ranked are out. Japan lost against Russia and Italy, but Japan is in semi and the other two are out...