Observe Bournemouth vs us.
Their DM gets the ball centrally (in the area between the CB's). It's what the RCB does now that shows why we can't build from the back. The Bournemouth RCB drifts wider and steps forward into a right CDM position horizontal to the DM that allows the RCB to do the job of the DM (if he's covered).
This is coaching, pure and simple. Not a matter of quality. They say we can't build up from the back, yet, during LvG's tenure we had the highest ball retention rate in the league and the same "poor" technically deficient defenders were able to bring the ball out.
Go ahead, check the average defensive quartet/five for LvG and see if it isn't almost the same as what we have now.
Coaching, coaching, coaching. If Bournemouth can do it with Ake and co, I think we can do it, too. Matter of fact, history shows that we have done it......... with the same defensive partnership.