The problem with sorting out the midfield or defence without sorting out the fullbacks, is that in a years time, we'll be back here talking about how "shite" our midfielders are precisely because of how important modern fullbacks are.
The magical midfields of Liverpool, City, Bayern, Chelsea, Madrid etc are as good as they are, because the fullbacks in those teams are part of the midfield. The "terrible midfielders" in our side are as bad as they are, because our fullbacks aren't good at their own jobs, let alone playing a part in the midfield.
We want guys who can play under pressure, who are technically good enough to work the ball out of tight situations and up the field efficiently. To do that, they need passing outlets they can trust to play ball with, no matter how good they are themselves. Those outlets are never going to be found in Wan-Bissaka or Telles.