The setback means the Whites have lost four of their previous five fixtures.
Hasselbaink criticised the midfielder in the wake of the defeat after his mistake allowed Joe Lolley to break through.
He said: “Normally they do the simple things really well, that's why they are so effective.
“This is just a hook, a simple hook it back. Why do you have to bring it down? I have no idea.
“It's two vs one and Joe Lolley takes it off him.
“You just have to play it simple and put it back, it's the last 30 seconds of the game.
“Lolley shouldn't even come close to it, he just has to hook it back and the forwards can have a battle.
“He wants to bring it down and, at times, you can not bring it down.
“The whole game he was making silly, silly decisions that weren't coming off. Other players as well, it was a Leeds I don't recognise at all."