Both have raised their games and shown the poise, skill and command which suits the All Blacks' plans and would be the envy of most nations.
Now they have the chance to push on in the end-of-year tour with some backup if necessary from Colin Slade.
However, coach Steve Hansen wants DC in the travelling squad which will be announced on Monday. The coach believes Carter's ability and influence on his teammates is an important building block as the group eyes up a World Cup defence in 2015.
That makes sense but fitting three, perhaps four five-eighths into four tests on tour does not.
That is interchange or rotation overkill.
Cruden or Barrett are the future and the present.
Both have been in great form this season and every time they step out in the famous black jersey, they are gaining more traction, more experience and test match acumen.
They may not yet have scaled the best goal-kicking radar and match analysis Carter dialled into during his premium international combat but they are on a par with his recent efforts.
Cruden or Barrett need to start the biggies on tour against England and Wales with the other to begin the test against Scotland. They can share some match time with Slade at Soldier Field in Chicago to have them all primed for the final three tests in the UK.
It's not as if Carter is a new boy on the block or needing a refresher course on the nuances of the code like SBW.
Carter needs more time away from the All Blacks in a sojourn which will complete his recovery and boost his craving for competition.