I can't imagine Guidetti leaving GER NT and going to Turkey. It's seems to be unfair to German girls who trust him a lot (as I know). I would understand some others choices but Turkey is one of the main rival of Germany!
As for Barbollini I can say that he used to be one of my favourites coaches. After London 2012 I'm angry at him but still I believe that he's a great coach.
There is no objectice reason for Motta's dismissal. In my opinion he didn't use all Turkish potential during the 2012 OG but in general he is doing a great job. It's stupid to change coaches so often.