The debate is reminiscent of the France series in 2013 when midfielder/outside back Rene Ranger played starring roles off the bench in Auckland and Christchurch during his team's victories, the latter a comprehensive 30-0 thrashing after a tighter 23-13 first-test win.
Radio Sport - Tana Umaga talks to the Crowd Goes Wild Breakfast
Ranger's form was compelling and similar to Savea's in that he added a spark off the bench through his power and willingness to get stuck into everything. Ranger started the third test in New Plymouth ahead of Julian Savea on the left wing but, by his own admission afterwards, couldn't get into the game.
He ended up trying too hard to make a difference and was eventually replaced by Charles Piutau in the 24-9 win.
The game at the top level is different in the final quarter due to the physical and mental pressures involved. Fresh players are able to take advantage of fatigued and fractured defences, and few are able to take advantage like Savea.
Cane was good at that himself as McCaw's back-up, scoring three tries in his first five tests. After making his test debut in 2012 as a 20-year-old, Cane has now played 33 tests, more than half - 18 - as a replacement.
He needs time to get used to the role, one of the most demanding in test rugby. Savea's performances will be putting pressure on Cane, but he must use that to get the best out of himself. For the moment, the best will be enough for Hansen.