Almost all of Real Madrid's players have speed, and a slow playing style actually makes them more not effective.
You're right, but Madrid's style focused on being a little slower thanks to Ancelotti, where they basically made good use of the midfield but now football is very fast, if you compare it to Barcelona's football you have to be fast and the forwards have to help defend, and generally Madrid's forwards don't do it, Vinicius doesn't help and that's negative, for me if he doesn't collaborate he shouldn't come on, Xabi has the same idea, so Xabi is building a totally integrated team without egos.
Ancelotti wasn’t lucky with the players Eder Militao missed a lot due to injury, Mbappe had to adapt, and Bellingham and Vinicius weren’t in the kind of form we know them for. I think Xabi already has well developed tactics and excellent training sessions that will generally prepare the players for the start.