I kind of agree, that most players SAF signed had good mentality. Sancho does not have one.
However, going against the manager/club in public was tolerated by SAF if you were a good player. Scholes refused to play and came back a week later, Rooney questioned the ambition of the club and got rewarded with a bumper contract, Ronaldo compared himself with a slave and we practically begged him to stay for another season.
But the issue is that Sancho is not Scholes, Rooney and Ronaldo. He is closer to a 75m Obertan. And when you are as useless as he has been, I think the right thing is to shut the feck up, train harder and get back in the team. Saying that, I think he was ok in pre-season, and probably deserved to play ahead of Martial and Antony, so for just a bit, I can understand his frustration. Standard are good, but should be for everyone.
To be fair, I think that Pellestri has more reasons to complain than Sancho. He definitely hasn't got a fair chance despite looking decent in the few minutes he has got.