Former Manchester United defender Rio Ferdinand described their Champions League exit as "embarrassing".
Ex-United striker Michael Owen said the club has gone backwards under manager Louis van Gaal and former midfielder Paul Scholes called them "average".
The trio were speaking after a 3-2 loss at Wolfsburg condemned United to the Europa League.
"This is a worse squad now. The players Louis van Gaal has let go would beat tonight's team," said Owen.
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United's defeat in Germany meant Wolfsburg finished top of Group B, while PSV Eindhoven, who beat CSKA Moscow, reached the last 16 as runners-up.
Van Gaal has been in charge at Old Trafford for 18 months and BT Sport pundits Ferdinand, Owen and Scholes have not seen any improvement, despite the club's heavy spending in the transfer market.
Scholes has previously stated he "would not enjoy" playing in Van Gaal's side as there is "a lack of creativity and risk".
"They spend £250m and can't qualify from a shocking group," said Scholes, who played 718 times for the Red Devils.
"It is more of a disaster when you are surprised. It was a shocking group. Will Wolfsburg and PSV get to the last eight? They will get knocked out in the next round."
Ferdinand added: "It's embarrassing. I was in a squad that went into the Europa League and it's an embarrassment.
"You don't want to come out of your house, you don't want to walk around Manchester.
"People look at you and think 'you're not good enough', questioning you as an individual and as part of a team that didn't get through the group stages that you should have.
"If you strip it back, this squad needs a hard look. There is no pace or power. People are looking around at each other rather than saying, 'I will drag you through'."
United are fourth in the Premier League, three points behind leaders Leicester, but have been criticised this season for their lack of flair and goals.
Owen reeled off the names of players who have left the club during Van Gaal's tenure who he believes are better than those who played for United at Wolfsburg.
"Rafael, Nemanja Vidic, Jonny Evans, Patrice Evra, Nani, Shinji Kagawa, Robin van Persie, Javier Hernandez, Adnan Januzaj and Danny Welbeck would all get in to that side," he said.
Analysis - BBC Sport's John Hartson
"If the Glazers, Manchester United's owners, want to carry on spending and continue to back Louis van Gaal then they must have money to burn, because Van Gaal will only make a hash of it.
"I really don't think they have made progress since David Moyes. I would change it now - his recruitment has been poor.
"I don't speak to Van Gaal's assistant Ryan Giggs that regularly, but clearly he will not be happy with the way they are playing.
"I just wonder how much of an influence he is actually allowed to have - whether he just puts the cones out in training. I wonder if Van Gaal does say from time to time: 'You know what? You give the team talk, because you are the next manager of Manchester United.'"
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Gary: "It's absolutely embarrassing. Louis van Gaal needs to go - there is no way we should be going out of a group like that.
"I've been to Europe with Cristiano Ronaldo in the team, I went to Barcelona [where United won the Champions League in 1999], I went all over when we were playing well. Van Gaal just does not have a team going. Not at all."
Adam: "Manchester United have got Sheffield United at home in the FA Cup and I really think it will be one of our lowest attendances. Nobody will go, because we are so dull and we are going absolutely nowhere. There is nothing to be excited about and I don't think we will improve - that's why Louis van Gaal has to go.
"We gave him £250m to spend, and only our goalkeeper would interest a top side. Nick Powell wasn't even good enough for Leicester when he was there."