Barrett said watching the game from the bench was a case of trying to stay calm and working at staying connected with the other reserves, being on the same page so they could understand the influence they could have coming off the bench.
"I was sitting next to Cortez [Ratima] and Anton [Lienert-Brown] and keeping each other calm and steady.
"I had 50 minutes to sit and watch, and analyse, to see how I could influence things. But, ultimately, when you get out there, it's on pure instinct."
There were a couple of key messages they drove to regain momentum to close out the game. But despite that, the game still went down to the wire at the end.
They got what they had analysed beforehand from England.
"But, to find that space under that line speed pressure is easier said than done. But, as the game went on, it sped up, and we found little opportunities as it broke up.
"It's just being on the same page, sticking to the game plan we've prepared for. It's nothing special.
"A lot of it is energy, giving us options to pull strings and talk us through, that and decision-making. We're prepared for that kind of intensity and heat from the English defence."
At the same time, it was hard for England to defend the whole field if they were going to come up fast and on a narrow front.
"It's effective most of the time, but if you're good enough to have time on the ball, and depth, those are the spaces that can open up."
His play in setting up wing Mark Tele'a for the match-winning try was 'just one of those opportunistic things that we took advantage of.' They prepared for it all week and the week before in Dunedin.
Barrett said the All Blacks had flirted around making convincing exits from their half without achieving them. But finally, doing that and applying some pressure on England was necessary at that game stage.
Pressure on both sides of the ball created a chance out wide when he made his spectacular break deep into the England half, followed by a well-placed speculator kick that fell short of his grasp.
"I found a little bit of space in behind, and that gave us a little bit of a lift."
In the game's final act, Barrett said he wasn't too sure about the obstruction rule at a maul that proved England's undoing; all he was concerned about was getting under the ball as English hooker Jamie George attempted to score.
Barrett said he was grateful for any opportunity to be in the black jersey again.
"Everyone wants to start and be out there from the first minute, but it's a competitive situation and I'm just happy to influence where I can."
Fellow substitute, prop Fraser Newell, said Barrett was outstanding when he went on.
"He showed why he's played so many Tests for the All Blacks. Having someone like that on the bench who can us young fellows down was awesome. He brings a lot of leadership."
Newell found satisfaction in helping to win a crucial scrum penalty soon after getting on the pitch. He praised the effort of the squad's non-playing members, who teed them up for their match-day experience.
"It's our job to set up the boys playing. They gave us pictures on what the England were going to bring at scrum time and it was awesome that we could go on and implement them."
He was confident they could sort the lineout problems they had in the fact of Maro Itoje's efforts.
"It's an area we'll have to tidy up because it wasn't up to standard.
"In the last two weeks we've gone through two games that have gone down to the wire and that builds a lot of character and trust within the team and that we can come on, still being behind, and come out the other with a victory."