Of course, Castro didn't want to take too many risks and therefore he sacrificed Mane to be replaced rather than having to cause problems with Cristiano. I hope that in the next match Cristiano will sometimes realize that the team's victory is above all else.
It should be that all players are wise. Logically, Mane is 31 years younger. He has better stamina than Ronaldo. It should be possible to replace Ronaldo is the right decision. Castro could replace Ronaldo with a defensive midfielder or defender and push Mane forward. This can be done to take advantage of the counterattack. In addition, they strengthened the defense. Losing 2 points is quite meaningful. With the condition that the difference in points is not much. Indeed, managing Star Players will be more difficult and it becomes Castro's burden.