It looks like United's management made a huge mistake when instead of "an inexperienced maybe interim manager" they hired another interim manager. Even if United manage to get some of the top coaches in the summer, it could turn out that the players have already forgotten how to be disciplined and how to behave under tough management, this is fraught with problems within the team.
A few seasons ago, people thought that main issues belong to coach position and fired Mourinho. Then they hired Solskajer with hope that he can bring Manchester United traditional mentality back. He failed and Ragnick came, almost failed too. Now, back to the main issues that very likely in their players. Professionality, discipline and attitude to contribute for the club with their best.
If players who receive hundred thousands of dollars per week don't contribute their best with good discipline in training and in matches, coaches can not do anything. It's time to get rid of unprofessional players in Old Trafford. They must think of this serious step first before considering of a better coach.