Sure, but I don't think it's wild to suggest that the attitudes of the former players, gets passed to the newer players. However, having said that it's impossible to get rid of everyone. I want players like Rashford gone. If we want consistency with a new manager, we need to continue the path Ten Hag was going for at least with regards to possession. Players like Onana, Martinez, Shaw, etc... are oriented towards possession based football. The next manager needs to demand we work towards dominating possession at the bare minimum. And if that's the case we need players like Rashford gone, Mctominay gone, and Bruno gone.
Going back to the players' effort, I don't think it's right that the players can lose belief that fast. They should carry out their instructions regardless. If United are a side that plays 6th-8th place level football consistently, then fine the manager is a clear problem and we can identify our squad needing huge upgrades.
However, there have been too many times where the players go from 2nd-4th place football and revert to football that is more deserving of those around 12-15th level. As bad as the coaching and the player quality is, it should never revert to that level. That to me shows that these players are downing tools or are incredibly weak minded.
That shows to me that even if we get a manager next season that starts doing well in year 1, eventually in year 2 or 3 these players will once again have another period of football where the football gets laughably bad like under Mourinho, Ole, Rangnick, and now Ten Hag forcing us to reconsider the manager. LVG is the only one that didn't have his players turn to absolutely near relegation level. He was sacked at the end of the season. We're on a worryingly bad trend of appalling losing streaks that get managers sacked.