Because for Boskovic it doesn't matter if their is one or two blockers in front of her but for Brankica is. It is easier to play with Maja she is waaay better setter than Naz.
Mihajlovic's performance is not due to Naz! Naz is making Busa shine whereas Mihajlovic is purely out of shape. She makes so many unforced errors. She is not as explosive as before. To me, it is very early to see effect of age. She is only 29, a lot of OHs reach their peak at that age.