My take on our center back situation. I wouldn't turn down an opportunity to for sure upgrade at the back. But but that token, upgrading there would mean that we are spending probably £25M + on a new CB, which in turn likely takes away some of our transfer budget for areas of more need (striker, winger, midfield).
Oh and signing Tuanzebe would not be an upgrade, that would be a sideways move and IMO a waste of money. We don't need another body in the position just for the sake of it.