Many factors influenced Madrid's streak. Rest being one of them. I didn't say play the starters all the time, a fair bit of rotating is reasonable. But one shouldn't overdo it. Keeping a player on the bench is not always good.
That's oversimplifying and acting blind... Vide supra for the rest...
Some of you are obsessed with rest. Of course, now it's ours to lose, main players' minutes should be reduced. But keeping the tempo, staying in rhythm is equally, if not more, important.