I disagree with this. Our CBs hinder our build up play massively. Smalling gets deserved stick for this but outside of Bailly and sometimes Lindelof, our other options in Jones and Rojo are simply poor and/or risk averse.
I've lost count of the amount of times when one of them has the ball and refuses to bypass a square ball to their partner to make a direct pass to the FB on the opposite side of the field who is standing in acres of space. These are not difficult passes and ones I see made by CBs at top clubs routinely. This slows up our build up and the additional pass which needs to happen often means our FBs, who are also problematic in possession/attack, are closed down without space to advance the ball.
Additionally Smalling, Jones and Rojo are all reticent or unable to do anything in possession aside from playing square passes or directly to Matic, Pogba or Herrera when they drop on top of them to collect the ball. It's a major source of our issues and affects our entire structure as players drop deeper and deeper to get involved in the build up play.
I'm not saying Toby fixes all of these issues, but his quality on the ball is so far ahead of anybody we have currently and defensively he's at least par with whomever you want to say is our best. As long as he's not in physical decline he's a clear cut upgrade over what we have and, imo, a necessary one.
The next step, if we were to sign Toby, is to then sell Jones or Rojo.
We would have to sell at least one of our current lot as otherwise we would have 6 CBs (7 if Tuanzebe comes back) going into next year.