I don't want want to write an essay here on how he mismanaged youngsters cuz there are so many examples, I will bring just one example in the case of Malcom who was only 21 years old. Why he wasn't given proper chance? Valverde barely used him and when he did he performed well. In one of the games he was featured the Clasico, it was actually shocking playing him (came in as a sub) in very important match since he didn't play much before. He was one of the best performers that night and scored a goal. His reward was not including him in the squad list for the next game. Now think about what I said in the previous post and it might make sense to you.
And man-management is in every sector, not just sport
. It seems that you never managed anyone.