All 11 players were changed at half-time, with Sam Smith's first-half strike proving the difference. Carrick was encouraged by how his second-half team, despite its youth, controlled the game without finding an equaliser.
"I was really pleased with the second-half team," Carrick told MUTV. "I thought they controlled the game really well against a team that is not easy to play against. They make you work for it.
"They can play long into Kieffer Moore and JD [Jacob Devaney] playing centre-half, it's not natural to him. He's played a little bit there but not a lot, I thought he did ever so well. In general, the boys took responsibility and showed their quality.
"Again, that final bit of trying to break down a lot of bodies in front of the ball, at this stage, it's not easy to find that sharpness and that extra little bit of creation. But that will come. I was really pleased with the young players [in the] second half and they can really be proud of themselves."
Jacob Devaney, who spent last season on loan at St Mirren, partnered Dan Armer at centre-back and handled Moore's physical threat well ahead of the tour continuing in Norway against Rosenborg next week.
"For sure," Carrick said. "He had a really successful few months up in Scotland. It was good to see him take that next step. The confidence and assurance in his game, even though he was playing a slightly different position. He was vocal, he was commanding. I liked a lot of what he did today."
Tyler Fletcher wore the armband after the interval, having enjoyed a breakout 2026 that included a spell with Scotland's World Cup squad.
"He's had an eventful three or four months, Tyler," Carrick added. "He didn't want long off [after the World Cup], he wanted to get back into it. He took that responsibility and led the team [in the] second half really well."
Carrick also gave his first verdict on Santos, who joined from Chelsea this summer and could become a long-term successor to Casemiro. The Brazilian recorded 93 per cent pass accuracy, four defensive contributions and two chances created in his 45 minutes.
"There's loads of little positives to take from the game," Carrick said. "I thought Andrey and Mason [Mount] did some really good things and connected really well. I could see some positives there. [At the] top end of the pitch, just because it is a week in, those sharp little movements and bright moments that you are looking for, they come as you progress through the weeks of training. There were good signs from Andrey on his first one, he's getting in the rhythm and feel of it again, so it was good to see him in a red shirt."
The priority, Carrick stressed, was minutes and a clean bill of health as Manchester United returned to action after 55 days without a game.
"As I said before the game, the boys have only been back together for 10 days or so," he said. "It was just about getting through today, looking for some positives, looking for some good things and knowing that it wasn't going to be perfect.
"That is only natural for the first one. I think the most important thing is that everyone came through it in good shape. No injuries, so we can move on and take the next step next week."