Don't know why Erik Ten Hag's tactics are not so effective and we know the formation arrangement he does is also less interesting in my own view, he always plays players who are less impressive but are forced to play full, for example Rashford has played several times badly but Erik Ten Hag still believes in him.
The manager has given a lot of support including the transfer of players he wants, if this does not go according to plan then there is a possibility that he will be fired, if his team continues to lose and Erik Ten Hag is retained, this will be a lot of pressure from fans.
Ten Hag looks to have problems with his tactics and player picks. You can have good idea for your tactic but it only works well if your favorite tactic can be executed well by your players. The second component is important, it is players and a good head coach will know that with available players, what tactic can be used to maximize ability of players in the team.
If a head coach only uses one tactic and does not mind to change it even many players injured and rest available players can not play that tactic well, he is a very bad head coach. We can look back and see that with Sir. Alex Ferguson, many normal players played well and together helped Manchester United to beat opponents and got many winnings.