Real were undone against Barcelona in the Copa by a set piece.
And Mou said: "Numbers speak for themselves. Since the start of 2012 we've conceded two set piece goals against Malaga, one against Mallorca and one to Barcelona. That's too many. Sometimes in order to avoid making the same mistake it's good not to dwell on it too much. We're aware of our mistakes and also of Athletic's set piece potential."