From there he can be injected at fullback and give the All Blacks two first receivers and decision-makers either side of the ruck. From fullback, with 30 minutes left in a test, he can use his extreme pace to blast past tired defenders and spark the All Blacks into life.
He makes so much happen in the last half-hour that he's almost trapped himself with his contribution.
His only way off the bench is to prove he's the best option to start at No 10. He has to convince the selectors that he can match Aaron Cruden's timing and impish agility. He has to prove he can read the game, see the big picture and, perhaps most important, he has to match Lima Sopoaga's accuracy in front of goal.
Between Barrett, Cruden and Sopoaga, the All Blacks have the perfect No 10, but unfortunately they can't wrap all three into one player. At the moment, the closest is Cruden. Though he hasn't goalkicked much for the Chiefs this year, everyone knows he can and that he can also get better at it.
Of his 36 test caps, he's started in only eight and two of those were at fullback. The question for Barrett is: how long will he be content play a secondary role?
The All Black coaches have clearly thought about this, because they have elevated Barrett to the leadership group. That suggests they will be looking to build Cruden and Barrett together.
There may not be a definitive pecking order as such and they may look to swap who starts, depending on the opposition.
Coach Steve Hansen wants Barrett to be a world class No 10 as much as Barrett does. Hansen needs him to be, because first five is a high-attrition role. Just as they didn't want to be overly dependent on Daniel Carter in 2012, the All Blacks don't want to have all their play-making eggs in Cruden's basket. They need Barrett to be capable of driving the game and kicking goals, and that's not going to happen by confining him to the bench all year.
There would also be some concern that, without some sense of progress, Barrett could be tempted offshore.