Okay I know this is not the right place for this response but here goes anyway. Charlie has obviously made a conscious decision not to acknowledge the players, the players must know this and I assume they get their praise or critisim later.
My theory - Acknowlegment in the heat of the moment could make a very public gesture, either positive or negative. If he acknowleges some but not others then I think that would be a bigger problem. We would then all be reading things into how he responded to each player. We know he is a passionate and potentially heated guy, so I suspect he is much happier to show how he feels about the players performance in the dressing room and not from the dugout. He also keeps his focus on the game, not worrying about how he should respond to the player or if the player isn't happy at being hooked. I know it's unusual, but it seems to work for him.
I know the players have a lot of respect for him and Parkie so I don't think it causes any unrest within the team. It's just fans that seem to have a problem with it. We won't change it so best just accept that's the way he works, and for now I'm happy to go along with that if the results keep coming.
Sorry - Rant over