The most important part of the team is the defensive line. In fact, if you don't have good defenders in your team you can't get good results because even if you score goals and have good forwards, still your team will easily lose and that's what happened in the game against Liverpool when they scored three goals in one game. Manchester United should hire better defenders and have better teamwork, this will make Manchester United a much better team but I think they can't have this with their coach Ten Hag because of the bad defensive line they had in Manchester United.
Man United actually already has a good defender like Leny Yoro but unfortunately the problem that MU experienced last season happened to the player who was injured. I don't know what caused all this but I see Man United more often injured players. This is the reason why Man United performance is a little bad but I also support your opinion if Ten Hag should prioritize new players in the defense line to maintain stability between the attack line and the defense. This is a pressure for the coach, he must continue to fix this problem with the many criticisms that are currently spreading. Ten Hag should have a strategy to cover this weakness by not losing the score in every appearance.