If two contenders are at a similar level they generally select the one who is staying. Clearly in this case, they do not feel any new halfback is kicking down the door to warrant inclusion, even from a development standpoint.
The other complicating factor is, as it stands, Kerr-Barlow and TJ Perenara are probably neck and neck. Neither is the clear second choice behind Aaron Smith.
A clutch of halfbacks wait in the wings. Mitchell Drummond has enjoyed a quality season for Canterbury - his support lines and accurate pass gaining attention.
Bryn Hall made giant strides since leaving the Blues. Augustine Pulu, who made his test debut in 2014, doesn't appear to be in the selectors' thoughts. While his dangerous running game and abrasive defence are assets, delivery and decision-making from the base may not suit the pace the All Blacks like to play.
Brad Weber, another to feature once for the All Blacks in Samoa in 2015, ticks the speed of pass category but has just returned from a broken leg.
Taranaki's Te Toiroa Tahuriorangi, signed to the Chiefs next year, is considered a talented prospect. The 22-year-old hasn't done enough at Super Rugby level yet to justify a call-up but may not be far away. Northland and Blues 21-year-old Sam Nock is another in the bracket of emerging nines.
The situation at halfback is again a talking point after the loss in Brisbane where Perenara did not have the desired impact off the bench. With one quick tap and kick he almost scored a brilliant individual try but after that some of his other kicking options and decision-making in the final quarter was questionable.
The All Blacks finished the match with an unfamiliar halves combination in Damian McKenzie and Perenara. Other than his outing for New Zealand Maori this was McKenzie's first crack as international No 10, and it is perhaps no surprise this combination was unable to deliver the clutch finish we have come to expect from this team.
Players in these roles must assert themselves and be drivers. On this occasion, and not for the first time this year, there was a noticeable dip when Smith was replaced.
This is just one area the All Blacks will target improvement as they head north on Friday.