We are talking about footballers and a manger, I'm sure they know when they've had a bad game and therefore can come to the conclusion that the fans won't be happy. I don't always clap them off, when the game finishes I sometimes just stand up and leave my seat, I don't see the logic in booing, especially when people do it on a whim or too easily, for example at half time.
With regards to the management, I can have an opinion on whether he is right or not but it isn't up to me whether he should be in charge, that's Knight's decision, just like your boss at work, you wouldn't go and tell him he wasn't up to it, would you?
Every player will know when they have had a bad game they don't need telling. I bet Hawkins was devastated about scoring an own goal last week he didn't need people abusing him off the field.