In retrospect, it seems to me that Ten Hag was at fault in each and every fight he had with players! He is stubborn, he has some ideas but he cannot adapt them to the actual players he has available, he cannot really understand who has what talent, and he has favorites. All these are serious deficiencies, especially for a top manager. As a top manager, you have to understand what each one of your players can do and cannot do, and somehow find a way to inspire them to perform at 100%.
For example, we don't really know what exactly happened between Sancho and ETH. But we know that last year ETH was constantly using his boy Antony on the right, despite the fact that he was not performing. And then in the summer, he tried Sancho as a striker. Perhaps Sancho told him "Mister, I am not a striker". Why ETH did not try Antony as a striker? Antony has been useless on the right. But of course for ETH "Antony is unstoppable", so he has to play in his favorite position. Naturally, Sancho was upset that ETH so blatantly prefered to play an inferior player. This does not mean that Sancho does not have deficiencies. But it certainly means that ETH is not good at managing.