I'm not so sure Modric is the right player for Madrid. In Madrid's 4-2-3-1 formation the 2 center midfielders have a lot of defensive responsibilty. Let's be honest, Modric is shit while defending.
He is a technical genius with the ball at his feet though. Modric is better in a flat 4 midfield, like how Tottenham and Manutd play. And even better in a midfield 3, like how Barca or Chelsea play.