I keep coming back to dias thread because I really think that he changed our season defensively and it was so important for the treble. I am not sure when we last lost a match while he was on the team!
Pep said in the post match interview, "what different with this team? they defend better and they defend (with aggression)" . Ruben brings that calmness in defence. He makes the players around him be calm and enjoy defending.
Wherein previously we used to cruise every game but somehow lose the game because we were more focused on the build up play rather than defence. Ruben is the balance pep needed to win UCL. Even if we had a one off nervous bad game, defence is there to save the day until we score and win!