Manchester United management can decide to keep the manager or fire him after considering how Manchester United performed under their manager last season. After taking charge of Manchester United team last season, the manager could not bring any player to the club but this season Manchester United has brought three new players to the club so Manchester United should have confidence in this manager for the entire season. If Manchester United manager fails to bring his team to a good position this season then the decision can be taken to remove this manager. But if the management decides to remove this manager now then it will definitely be an injustice to this manager.
I think it's too early if the Management of Manchester United is thinking about the fire of a new manager. Because everything takes time to adjust to a new place . And the performance of the team in the last season was too bad and the previous coach left the team in a destroyed version. So the condition of the team is a challenge for the new coach to bring them in the position where they present themselves in a good way. So, the relation between the players and the coach is also taking some time to develop a great bond. It's very necessary in any team to have good chemistry between the coach and the players. So it will be so unfair if the management fired the new coach without giving him appropriate time to grab the team in the best zone. And i personally think he will succeed in making the players into a good team.