Another part that will be crucial for GS's success is how Eylül will perform since their weakest position was libero this season. Eylül is a great defender but mediocre receiver so I don't see her as an upgrade to bihter but hope to be proven wrong
Since I cannot be 100% sure about Eylül's performance in those areas, I cannot say you may be right or wrong. Time and their performance will tell us. If Bihter keeps her latest shape, at least I can say that Eylül may cover her, when it really matters.