United were hapless in defence in the absence of captain Harry Maguire, with Keane labelling the errors “schoolboy stuff”.
Ole Gunnar Solskjaer denied his side were lacking motivation, having already secured a top-four finish, with the club’s main focus now on the upcoming Europa League final.
Keane said the performance epitomised the gap between United and champions Manchester City and said that Solskjaer’s current squad will struggle to challenge for the title again next season.
“I know [Ole Gunnar Solskjaer] perseveres with Fred, but I can’t see it,” Keane told Sky Sports. “How they think Fred is going to get Man United back to winning titles is beyond me, I know he dragged him off. But it’s just sloppy, it’s lazy, he’s hoping one of his mates gets him out of trouble.
“We’ve just mentioned it, Shaw, it’s schoolboy stuff, it sums it up and then Liverpool are on the front foot. Then, the goalkeeper, who didn’t look great tonight, mistake after mistake – poor, poor from United.”
Keane added that the absence of Maguire should not excuse the poor display.
“Maguire is a loss but these are schoolboy errors,” he reiterated. “Fred is under no pressure there, gives it away. Shaw, an experienced international player.
“We’re building the goalkeeper up and asking if he’s going to be the future number one for United, but they’re falling short. Maguire is a loss for them, but that’s schoolboy errors there, nothing to do with missing Maguire.”
Keane also said that Henderson looked “small” in goal, with the goalkeeper guilty of poor positioning for Mohamed Salah’s late counter, and suggested United are yet to find the long-term solution to replacing David De Gea.