We're trying to become a CL winning team. If you think we can get there with a 32 year old Yaya, Fernandinho, a pretty average player in Fernando and Fabian Delph then we're going to strongly disagree
We have 4 senior centre midfielders too which just isn't enough for the season ahead.
There is definitely a gap in our centre midfield.
It would be suicidal to play Pogba and Yaya together so Fernandinho has to play.
Yaya is not going to be benched and pogba will demand to play every week as well. These players do not accept rotating, and cost too much to be on the bench anyway. KDB arriving rules out 433.
There is no space in our midfield for another starter. At best we could buy a back up for Yaya who has enough promise to maybe replace him one day.
Also look at barca's midfield. Their back ups are sergi roberto and Rafinha. That did not stop them winning the CL.