The decision to rule Beauden Barrett out of the All Blacks' test against the Wallabies in Brisbane on Saturday was clearly made on medical advice - but a key factor was his own reporting of his symptoms. In a changing climate, which suggests head injuries are now being taken far more seriously by almost all involved in rugby, this is another example of perhaps the most significant of shifts.
The All Blacks first five suffered the injury in the test a fortnight ago against the Springboks in Cape Town. He left the Newlands pitch and passed the Head Injury Assessment (a complicated series of random questions and physical co-ordination tests) but did not return to the field.
During the week in Brisbane he reported headaches and therefore did not train with the team on Tuesday. The symptoms severely restricted his training - as rugby's concussion protocols dictate - and in reality, Barrett, the leading No10 in world rugby, was always an outside chance to be available for the test at Suncorp Stadium, and his place was taken by Lima Sopoaga.
There is a constant pressure on players to retain their places, pressure that in the past may have prompted them to ignore injuries, including headaches. Thankfully that culture appears to be receding at the elite level because the consequences of playing with concussion can be life changing or even life ending.
The science around concussion is evolving but most sporting bodies are at last recognising how serious it is. As the world's No1-ranked team since 2009, it is good to see the All Blacks taking a leading role here. They don't always get it right, but their determination to err on the side of caution is to be commended.