I do agree with your assessment of the players I just find it difficult to give most blame the managers. Here are some quotes from Van Gaal that I think helps put into perspective how much blame they should receive.
Van Gaal told
Voetbal International: 'Manchester United did not have the qualities to become champions and had an outdated selection with 10 players over 30, five over 35.
'So I told them I was going to rejuvenate and which players should come. I didn't get one of those.
'Then you end up in a different segment and as a coach you have to push your boundaries. You don't expect that at the richest club in the world.
'A turnover of £600m and can't buy the players you need. You should buy number one and not number seven.’’
He is saying they got him 7th choice targets, I am sure just like Mourinho that they wanted world class players or talents. I am assuming that they were told that it’s either these players or nothing. In that respect then I do agree that they are guilty of not caring about the clubs money. They should receive a lot of blame for accepting players they didn’t want.