They did that because Zhu's reception was not that good. Her reception improved considerably this year. She received better than Kelsey in a lot of matches.
I agree with you in general, but during the clutch time when you only have one consistent scorer, I would not allow Feberbahce to force you to go to 2nd/3rd options by targeting Zhu on serve. That's always my point, even if Zhu has the best reception in the world, the other team would still target her on serve especially during clutch time, because she is such a great attacker. Why would Vakifbank allow that to happen so easily?