The Red Devils officially unveiled ten Hag to the media on Monday, and he will begin work with his assistants on reshaping the squad ahead of the summer transfer window.
While Yorke admits there is some optimism around the arrival of the new man, he also indicates the challenge facing ten Hag is enormous.
“We [Manchester United] are nowhere near where we are supposed to be, especially with the players that we have in the squad at the moment,” said Yorke, as quoted by France 24.
“I spent the last two weeks there and had some more insight into looking where the club is and why we are in that position.
“He’s [Ten Hag] got some major surgery to repair there, there’s work that needs to be done.”
He added: “I’m not sure what his first step needs to be but he must stamp his authority on the team in terms of getting the players united together. That seems to be a bit of a challenge at the moment.
“When you look at our squad we have some fantastic players but the achievement doesn’t add up to it. There’s some major ground work that needs to be done.”