Because he is our best passer of the ball (probably the best in the prem) , our who game is based around him, he takes the ball from defence or DM he sets up nasri and silva and our whole play goes through him.
Because alone he has the ability to drop a 60 yard ball in to Sergio, because alone he has the ability to run straight trough the middle of a whole team, because in full flight he is incredibly strong and capable of being very direct, because he alone can smash the ball in from 30 yards out whilst the ball is moving.
He is far and away our most important and most versatile player and he can break up tight games.
When we replace him with Pogba we need them to play together for a year or two.
The feckin clowns who abuse yaya and belittle his performance , who want him gone don't know football or don't care about winning