Not blaming the owners first means you know nothing about the club, Erik Ten Hag wasn't backed with the names he wanted for Manchester United, the players he brought in are player's he has worked with one way or the other before Manchester United and he can look back and say, this player can impact in this role.
Ten Hag was given lot of money for transfer and Manchester United agreed to buy many players on request of Ten Hag. It is not like he wasn't backed by the club to develop the squad and train players with his philosophy. I would say he got more support from the club than previous coaches from transfer money to how he was given power to handle star players in the club.
It's just obvious that they spent the money on players that can't be at United level. I mean we are talking about a United that was the last team at their UCL group stages, they were worse than Copenahgen who went to Last 16 at UCL, lets say this is somehow acceptable after spending that much money, which it is not, but they weren't even third, that was Galatasaray who will keep playing at Europa, and United became fourth place as well.
I know that it is not going to end up with anything good after this. They are not finishing the season last place neither, it should be something important to realize that it is not going to end up being any nice at all, they need to figure out something, or just fire ETH at the end of the season and get someone better.