Do you even read what you write. It helps sometimes.
Sachin scored his double century in 147 balls. He did not take 300 balls to complete his double century. His double century definitely helped India to win the game.
If Sachin is playing as well as he is now, why should he leave his place for a new comer. In the same vein I might as well ask why isnt Raina leaving his place for a new comer…