I agree that Man United's defense is very fragile and makes mistakes a lot. I also don't see Harry Maguire making a good contribution to
Man United since he was bought for a very high price. And Maguire's selection of captaincy is questionable, because I don't see Maguire can
motivating Man United players. I agree that Man United should get rid of Maguire and buy a better defender.
In my opinion, Maguire is not a top-notch defender but if we skip all of his contribution for Manchester United, it is not right and not fair. When Maguire came, he helped to improved the defense system of Man United. What happened is players around him are not good especially his team mate in the centre. The club tried to fix it by buying Varane from Real Madrid but so far he spent more time in health recovery than real matches.
But the most important thing is that Man United must immediately find a replacement for Solskjaer. because some Man United players have reportedly lost faith in Solskjaer. If left like that, Man United players will not be able to bring out their best abilities.
It is not only about faith but also about the system Solskjaer has built up for the club after 3 years there. I don't see clearly what tactic he builds for the club. He drains his favorite players' energy a lot and don't care to protect them in unimportant matches. Then in important matches, for titles, example, they were exhausted and the consequence is their bad performance that in turn results in failure in final matches. No title at the end, something like this.