What I've noticed and don't know if anyone else has noticed, might be why Pep was so adamant in the post match press conference about CDM. But Peps entire tactics not just for this City team but his Barca , Bayern and some of the best City teams we've had treble/Centurion.
The number 6 is the most important postion on the pitch , the most important postion in his philosophy and tactics, without a very good 6 , Peps tactics of control fall apart. Busquets , Fernandinho, Rodri they keep control in the midfield.
You can see when Pep doesn't have a good number 6 we look vulnerable easy to break through and break down. The 6 postion in a Pep team controls everything in that midfield. Even though we had Kev and Gundo in the treble season Rodri controlled everything with his passes and tempo. Same with Fernandinho watched some old games and he controlled everything in that midfield.
From the start of playing out to launching attacks. The 6 is the playmaker and orchestrator. Right now Nico G is learning and he could become a very good number 6, but when he went off we lost all control. Or when he gets tired we lose control such as against Leeds.
I don't think it's Peps tactics I just think Peps number 6 is still learning and when it clicks all these defensive issues will go.