I'm not sure what would happen if Ten Hag were to fail to make it to the top four this season for Manchester United, but it would certainly put him under a lot of pressure. The Champions League results will likely put him under a lot of pressure if Manchester United lose and fail, but I still have confidence in his tactical abilities.
One thing that is sure to happen to him is that lots of pressure will definitely mount on him. Last season he managed to get the clubs first silverware after 3-4 season and then help guide the club back to the biggest European competition and this was what earned him the fans support. This season he is yet to get off to a great start but one thing is the season is still young and there many games to go but should things proceed to get ugly as it goes then I think United fans will asking for the departure of the manager.
If you ask me I would say unite can actually bounce back this season to go along away. The first thing to do will be to start getting points away from home especially against the top clubs. This has been a continuous problem since the arrival of Ten Hag to the theatre of dreams. He is currently on a very good run at home but the away record is just too poor and should it be adjusted to like that of the home record then it will be a big threat towards the other teams but should it remain like this then I doubt they will genuinely challenge for the league