Friendly matches are not really important, especially at this period of the time when most of the teams are in training camps or they are still hiring players. I think the best we can do to know the performance of Manchester United is to wait for the first weeks and first games in the next season from Ten Hag and his players.
It's important for the manager and we can start to analyze how good the team was. The fact that if so many clubs were also using the pre season to measure how good or bad the team is. Manchester united's performance was convincing me to think that if MU may able to perform even better compared with arsenal. Arsenal is always getting panic once it was facing fast counter attack. It has proven by how two goals being made caused by counter attack that came from manchester united.
Manchester united is ready to be the same as manchester city very soon. Arteta needs to think ever harder to strengthen its defensive line especially when it was facing fast counter attack. I doubt if arsenal will able to perform like last season.
MU has more chance to perform even better next season. I guess that if everything can happen in the future but my belief if MU will be waking up again to compete with manchester city. Chelsea was also getting good result.