Without Yaya our whole style of play falls apart. He keeps the whole thing ticking taccy over.
Silva is a luxury player, who atm looks totally lost. He should be dropped never mind rested.
Nasri is beginning to get the bit between his teeth.
Never thought it was viable playing both in the same team, especially away from home. I have no idea why RM persists with this flawed idea.
I guess it is because he's stubborn.
Going back to the OP. Yaya is far more important. Quite simply an awesome allround midfield player. Can score, more than Silva. Can pass and can defend. What more would you want?