After 4.Nxd7 Rxd7 Black has a long-term edge thanks to the weak e5-pawn, so White opts to transform the position.
  White keeps the d5-square under control, without worrying about the doubled c-pawns.
  From now on the ...d6-d5 break can be discarded, and Black is also suffering from a backward pawn on d6.
  Preparing a consolidating f2-f3, as well as Rab1 with a fight for the b-file.
  