Which is why Barrett is able to have a direct and significant influence on test matches. He's viewed, both internally and externally, as a critical part of the set-up and he's getting game time - usually entering the fray when those around him are tiring and his fresh legs and clear head can make maximum use of the opportunity.
"I used to be fully focused on being the best player which means you have to be starting to be that," says Barrett. "But now it is more about playing for the team so that could be coming off the bench or that could be starting. Whatever role I'm in, it's the same ... how can I be the best player for the team? That's how I prepare ... who knows ... if I play well, keep playing well, putting more pressure on? But I can't control selection. Training and playing well are the only things that I can focus on.
"I think if I am not disappointed or gutted at not being selected to start then I'm getting too comfortable and I am not doing it for the right reasons. I'm ultimately working as hard as I can to get a starting role - don't get me wrong about that - but the most important thing is that I do role for my team and that is coming off the bench most of the time."
It's understandable why the All Blacks coaches like him in that bench role and why they will be particularly interested in seeing what damage Barrett can cause this week.
There's little doubt Wales are nearing the end of their limits. The last half hour against the All Blacks this week could be especially challenging for them as they battle fatigue.
Barrett could be in his element. On his home ground, with the Welsh wilting and the All Blacks potentially going to have found better flow and cohesion, he could run riot.
He says he prepares to be injected at either first-five or fullback - that his training week is spent trying to suck up as much information as he can so as come game night, he's able to operate more on instinct.
"You want to get your head around both roles so that when you take the field, you are clear, you are not worrying about where you have to be. You are playing what you see and that is important for me covering two roles.
"That preparation is important so I can just get on there and play."
His patience seems like it will, at some point this season, be rewarded with a start in the No10 jersey. But for now, he's happy just where is.