Pre-season games usually don't have any motivation for the top clubs to win the game. Yes, I agree that in this match both teams gave one hundred percent of their abilities. But this is not the first time a top team from the English league has lost to a mediocre team. I think Manchester United really made this a game to test a lot of different tactics. Rosenborg scored a goal late in the game so I think both teams played very well. But a defeat is still a defeat and Ten Hag also said that this was not the performance United should have.
If Ten Hag has started to realize this at Manchester United, of course he himself knows what he actually has to do before the season actually starts. Because in terms of time, it is still possible for Manchester United to make more evaluations and better strategies to be able to start next season as well as possible. And apart from that, losing in the pre-season match also didn't harm Manchester United even though it could make the mediocre team feel happy and enthusiastic enough to start next season in the Premier League.
Ten Hag is certainly a capable manager and he has been in charge of Manchester United for a long time, although the team has not done well under him in the last few seasons, but he has been given one more season to change the position of Manchester United. There was a good chance he could lose his job this season but with Manchester United finally relying on him, the manager will surely change his tactics and try to improve the team's performance. This season has been a gamble for Ten Hag. If he can show something good this season, Manchester United will definitely extend his contract, but if the performance is worse than in the past, then Manchester United management will remove him from the responsibility of the team.
If am correct, I actually don't understand what you mean by Eric ten hang has been in charge of Manchester united for a very long time, so if I may ask, is two years a very long time? And this season will make it his third year as manager of Manchester united, so it's best you don't exaggerate things, and as for his abilities, no doubt he is a very good coach, and he has proven to be a winner in my own perspective, but this upcoming season is definitely going to define his future at the club, wether they are going to retain his services or not, but if he did much better than last season, I believe that they are going to retain his services at the club.
I have said this before and am still going to say this again, the major problem of Manchester united is not the manager, it is how the club is being structured, they focus more on commercial activities than anything else, till that is amended, Manchester united will not return to the glory days we all know that they had during the days of sir Alex Ferguson.