A players old team's style has no bearing on how well a player will play here, but it definitely has an influence on our perception of the player. And it has an influence on the selling clubs perception.
When I ask 'what happened to coaching' I am being deadly serious. It's not at all cliche. We have 3 quality centre backs. Defences need consistency. How would be maintain any form of selection consistency when we have 4 players to fill 2 positions. Centre back units shouldn't be swapped and changed in the same way an attacking unit is. It relies far too much on organisation and knowing the tendencies and characteristics of your defensive partner.
Unless we suddenly think Lucas will be better than Stones and we are going to either move Stones, Kompany or Otamendi on, I don't see the logic in it.
Have you not seen an improvement in Otamendi this season?
So then don't ask what happened to coaching while asking Pep to spend his time coaching 30 year old left backs to play CB.
Also when you say "we have 3 quality CBs" it makes me think you're including Kompany, but surely no one is silly enough to expect us to rely on Kompany's fitness again?
Because when he gets injured then we have...2 good CBs. For 3 games a week. For the whole season maybe.