There is nothing Ten Hag can do to stop those players from leaving, because they have already made up their minds and have a new deal. However, they might not listen to him because they don't have confidence in him.
The players and Hag have little to say.
Players have contracts in place, they can hate Hag as much as they can if their contract is still 2080, they will play there till they are 100 years old!
Hag actually has less power than Freund or Eberl, and even those two have little to say if Dreesen is against it.
The world is full of stories of managers trying to get or get rid of players and not being able to do one thing and instead ending themselves getting kicked out!
@stompix this is dangerous terrain and I hope this is just parody!
Let me remind you 
I am sure you are confusing something here, ten Hag is not from Chinese and he doesn't owe anything to Freund, Eberl or Dreesen because ten Hag is a coach from the Netherlands working for Bayer Leverkusen, lol!
But in your case I know it's just a hiccup, some others never get it right.