If anyone should be held responsible then it is Ten Hag but to completely blame him, I think it's unfair because no matter what he managed to get the FA Cup trophy, and it's been quite a long time since Man United won any trophies. At least he is still worthy enough to be given the opportunity for another season, and if indeed what he is currently building is not producing good results, maybe that's when it's time to consider changing coaches.
If he is a good coach, I think Man United can be better than last season, but to make sure of that, there will be time to go through first.
Manchester United realistic target this season is to win the Europa League trophy and finish in the top four of the Premier League standings, Jim Ratcliffe will most likely fire Ten Hag if he fails to realize it. The club top brass will no longer want to swallow the sweet promises made by Ten Hag, the FA Cup is not enough to cover the club expenses and player spending, it is just entertainment. The guarantee given to Ten Hag until December, if he fails to improve the team performance then he must leave his position. It does feel unfair to say that Ten Hag is not the right person to serve as The Red Devils manager, but in many opportunities that have been given, luck seems to be not on his side. Hopefully this season he will no longer have conflicts with the players, and can also control the dressing room completely.