So many ways to describe where he played, because he played in several positions. His position depended on who was fit - he subbed in for Ronaldo or Bale up front for example. After Christmas and the move to 433, when everyone was fit, he played in a midfield 3 alongside Modric and Alonso but with obvious instructions to use his energy/speed to overload the leftwing allowing Ronaldo to go into the middle without the fullback tracking him.
He also played as a fast defensive right winger in a kind of 4-3.5-2.5(!) in a couple of big games, giving Madrid a true midfield 4 going backwards and a true attacking 3 going forwards. And yes, there were even times when he played a #10 of some sort.
In other words, he was not only incredibly productive, he was incredibly flexible. Ancelotti loved him for it.
The difficulty Madrid have with him is that they increased his pay after a good season, and he turned poor for the next 12 months, before turning into one of Ancelotti's key players. Now he wants another payrise and everyone wonders if it'll be followed by another 12 months vacation.