When the current season begin,in the first 5-6 matches Pelegrini used the 4-2-2-2 ( with two DMCs ,Lass and Alonso ) formation,but to be honest with average succes. Doing this he utilised Alonso as pure destructure,which is not his strenght ,and limited his great vision and playmaking style of play. Upfront there were combination of Raul and Benzema or Raul and Higuain. On the wings Ronaldo played some good matches,because even with that formation he has the freedom to cut inside,or even to spearhead the attacks,when Raul dropped deeper,and the other player upfron ( Benzema/Huguain ) moves wider to open space for Ronaldo. Still the team doesn't play good,and were vulnureble in defence. Moreso when Ronaldo get injured Pellegrini completely changed the style and formation,just to suit Ronaldo's abcent,and the talent of Kaka and Alonso. He starts to use the asymetric 4-2-3-1/4-3-2-1/4-3-1-2 ,or whaterver you want to called it ,where Lass was pure destroyer,covering the fullbacks,where Marcelo was winger,Alonso has move higher on the pitch to be the playmaker of the team,and Kaka was attackind midfielder,when mostly of the time Higuain filled the Ronaldo's position.
I think in the last month or two Real M showed very drastically how this new style is used by them.