Who do you think he showed this for? For Inter he often played ahead of Zanetti, Motta and Cambiasso in a 4312, or in a 4213 ahead of Cambiasso and Motta. That's at least two energetic holding midfielders behind him for the vast majority of his time there. For Hollans at the World Cup he had Van Bommel and De Jong behind him, one pure defensive midfielder and a tough-tackling holding midfielder, playing in a 4231. For Madrid he played in a 2 in a 4231 or on the wing, and he was the player subbed off more than any other Madrid player in his time there (which surely suggests something about his ability to go box-to-box for 90 mins) and looked defensively liable.
Modric on the other hand has played in a straight 442 for the vast majority of the last 15 months alongside Huddlestone - someone less defensively capable than Carrick - mainly, at times alongside Sandro or Palacios. To me someone playing in a 2 man midfield gets through a lot more work than someone in the hole in the 4231 - as can be seen by the huge difference in distance covered for Giggs in 'cm' and 'am' - and thus is more box to box.