Rule 11 in the FIFA rule book...Offside
A player in an offside position is only penalized if, at the monent the ball touches or is played by one of his team, he is, in the opinion of the the referee, involved in active play by :
interfering with play
or
interfering with an opponent
or
gaining an advantage by being in that position.
McBride was in violation of the second part....Had he been two or three steps to his left, it should have been OK....But with the knothead from Uragaury, who knows what would have been called...