I think that the criticism that Nathan is a 'system' halfback is valid.
He isn't the type of halfback who 'reads the game' and sets up plays 3 tackles beforehand like an Andrew Johns.
He isn't a 'natural' footballer like a Thurston who can play 'eyes up' footy, spot a half gap and throw a beautiful cut out pass on the chest for a linebreak.
He is an effort footballer who plays low risk football and stays calm doing it, is a great defender and is an excellent kicker which is arguably his best trait. Otherwise, there is nothing exceptional about him. He is a good runner without being great. A good passer without being great. A good decision maker without being great.
He is very much a manufactured product which makes sense when he is a Coach's son who isn't exactly a natural athlete.