We may blame Ten Hag's, he's in control and responsible for everything. The current squad cannot do anything for Manchester United, they must sign players during the transfer window. Consider Manchester United's defense line, Varane can no longer defend and there is no one to replace him at the moment. Even in their last game against Liverpool, Manchester United could not have equalized, if Klopp had not removed his top players.
It is the coach's strategy and the players he chooses to play are what give him the victory in the match. Despite these, the coaches are not the only ones to bring the victory alone to the club, it is a collective effort that requires the involvement of the management of the team. However, without being told, Manchester United needs to sign new players in the team, and Ten Hag won't agree to that alone without the approval of the managerial team of Manchester United. Anyway, let's see what will be their plans by next season cos I know for sure, they sign new players into the team that will strengthen the frontline and defense.