Maguire, 29, has been the skipper at Old Trafford ever since Ashley Young left the club to join Inter Milan in January 2020.
This season, United have conceded 44 league goals – twice as many as Liverpool – and are struggling to finish in the top four with critics singling out Maguire for his poor performances at the back.
Keane, who won seven league titles with the Red Devils, believes Maguire is not fit to be the team leader and he should not have been given the captaincy so soon after joining the club from Leicester City in 2019.
Speaking on LadBible TV in partnership with Sky Bet, he said: ‘I feel sorry for Maguire. If you go into a big club… it’s like, imagine if when I came to Man United when I was 20 or 21, quite young, and they went, “Oh, you’re the captain”. I’d be thinking, “That does not say much about the rest of the group!”
‘Surely someone has got to be at the club a number of years to be captain. (Who should be captain) at United now? The fact we’ve got to discuss it or think about it is not good. It’s not good.
‘Well, it’s not good that Maguire’s got it because he was only new to the club himself a couple of years ago. He was still getting used to (the club) and then all of a sudden he got that extra responsibility when he was trying to find his feet. ‘
During his three-year spell at Old Trafford, Maguire’s performances have gradually declined.
When he moved to United in an £ 80 million deal, the Englishman initially lived up to the heights expected of him and was part of a strong defense which conceded just 36 goals in his first season, just three less than the champions Manchester City.
However, despite finishing second last term, the Red Devils failed to match their defensive record of the previous campaign and shipped 44 league goals.
The signing of Raphael Varane this summer was supposed to create the defensive backbone needed for United to make a sustained title challenge.
Yet a ragged and injury ridden Maguire has played a significant part in the team’s struggles this season, with United set to go five years without a trophy and fighting for a Champions League place.
As the season nears its end, Maguire’s problems are mounting with rumors Cristiano Ronaldo holds doubts about his credentials as United captain.
Meanwhile, in March, he was heckled by England fans at Wembley who appeared to disagree with his selection in the team.
MORE: Manchester United boss Ralf Rangnick dismisses Erik ten Hag distraction and doubles down on Liverpool claim
MORE: Chelsea defender Antonio Rudiger turns down Manchester United approach
For more stories like this, check out our sports page.
Follow Metro Sport for the latest news on
Facebook, Twitter and Instagram.