My ideal formation based on potential and guys being 100% healthy:
Di Gregorio
Kalulu - Bremer - Cabal
Mario - Thuram - Locatelli - Cambiaso
Conceicao - Yildiz
David
If we could get Cabal back progressing and performing the way he was prior to his injury then I don't think we need to invest heavily on a defender.
I also hope we could get Koop back in there somewhere but to be honest I did not see anything at all last season that makes me think he deserves a starting spot.
Joao Mario and Cambiaso are real wingbacks fit for the desciption of the role.