Yes i saw, it's not that i like a 4-man defense very much, it means that he's putting all the effort into a defense rather than into the midfield for example.
I liked Carlo Ancelotti's game, so let's see if Xabi's works, we'll find out next season.
Xabi seems to adjust the formation used with the available players. Xabi in Leverkusen more often uses 3 defenders and 4 midfielders, which makes Leverkusen's type of game with dominant ball possession.
But it seems a different pattern is applied to Madrid, who have stronger players in the attacking game pattern. We have not seen how effective Xabi's method will be applied for next season. But hopefully, there will be no problems with the players and the playing style designed by Xabi.