Mourinho is being stubborn for sticking with this 4-2-3-1 rubbish. Pogba isn't a happy player I sense and like another poster mentioned it's no different to playing KDB at DM. How you can you put your main creative asset in a defensive role? Just look at the freedom he had against Everton compared to today. That is 100% Mourinho's fault.
He's playing CM. It's not a majorly defensive role. KDB has to do a shit load of tracking and defensive work in Pep's system. But it's easier to blame Mourinho than the player I guess.