For England he is correct. Yes you always need to prove yourself as a footballer to get picked in the team, but I don't think this is what he's referring to. I think he's referring to the implication that he's not good enough for England, shouldn't be picked for the squad because of his club situation etc. Which isn't the case, he's one of the best options of a bad bunch of centre backs. It's very clear this is what he means and the criticism he's attempting to combat because he goes on to talk about minutes played for United.
The United comments are a statement of nothing really. He's played some games and can't remember losing.