Obviously this game wasn't a priority for Madrid and that's why they had some key players who would have made them win stressfree staying on the bench all through the game , although Madrid concede goals that made their victory a slim one, Statistically Madrid performed well and so did leganes whom I'm literally seeing as tried enough to attempt equalising a game against Madrid.
As far as I know, Ancelotti always implements rotation in each tournament. he always says that every tournament is important for the team, and they must win it without disregarding the priority. Maybe because that rotation, making players not optimal so it's not so cohesive until the end of the match. This is real Madrid, even not so well at beginning of match, but the end result was as expected, they've already won and going to semifinal copa del ray. As we know, Real Madrid will perform optimally when at this stage. Most likely Barcelona, and Real Sociedad will go on to semifinal, and we'll see the same match as before.