I'm very comfortable having Mangala as our 4th CB, because if truth be known, it could be a lot worse. What we now need to do is concentrate our efforts on a world class CB, Sanchez & another LB to cover for Mendy in the next 2 windows & then we need to think about the successions of Silva, Yaya, Kompany, Fernandinho & Aguero.
Aguero has another 4 years left in him and Kompany has another 2-3 at most taking his injury record into account. Yaya may only have another 1 maybe 2 and Fernandinho possibly 2-3. We mostly have back ups for these, but when they move on, we need like for like replacements so the team can evolve. In this respect, we need to make Sanchez & VVD our priorities.