Hope it gave you an idea of what you need. I trust the mark my teacher gave me 100%, as he is supposedly a "legendary figure" in modern marking, as he had been doing it for 25 years (15 years as a senior marker)
By x factor, I think he meant it didnt blow him away. Maybe my argument could have been more sophisticated etc. But basically, my tutor (HSC marker for modern as well) marked it and he said it was a potential 24 but most likely a 23.