I would argue that he did drop Mata, McNair, Young, Herrera and Depay when they did not do what he wanted or perform as he wanted. Maybe even Schniederlin. There is also an argument to say that he did it with ADM. He chose the players, so there is no defense for that, and he will be accountable for that.
Maybe I am just a different breed from some of you, and we have probably all played the game, but I doubt very much whether any of our abilities dropped just because the coach said I want you to man mark him, or stay out wide, hold your position. We have probably all had games where we just didn't feel right physically or mentally and it affected our game. That is not the fault of the coaches or managers. If he doesn't do something about it during the game, if he has the luxury, then sure he should get what he deserves. But not all player performances are the managers fault. Also, when a player like Depay does the header at Stoke, Adnan in the Southampton match, why turn on the manager. The players fecked up.