Erik ten Hag's future as United manager will be determined in the coming weeks, with his team aiming to secure a place in European competition for next season and complete their campaign with the FA Cup final against Manchester City .
Keane suggested the United manager must accept his failure to find solutions to recurring problems in his team.
“You can't avoid the manager's responsibility,” Keane said on the Stick to Football Podcast.
“The bigger picture is that something is not right on the training pitch. If you said give these players to (Jurgen) Klopp or Pep (Guardiola) – world-class players – would I think they would get more out of it? Probably. So that's where the manager has to look at himself.
“He looked isolated on the sidelines last night. He looks at the staff around him, but you have to bring something to the party, create something. It just doesn't happen.”
Today's sports news in 90 seconds – May 10
Keane then wondered whether the game's top players would want to join United this summer as the team falls further behind the trophy chasers.
“You wouldn't want to sign for United at the moment and the player has to take responsibility. Sometimes you have to go in and find your own form to have an impact,” he continued.
“Whether it's (Mason) Mount, where players get injuries and so on, but you have to go into an environment, from my own experience of going into a club, where you go – you have to walk into a good environment dressing room – where you thinks, listen, there is a bit of momentum at the club, there are people making the right decisions.
“Maybe United, despite all the bad decisions they've made over the last five to 10 years, might get what they deserve. If they're making such bad decisions at board level and in recruitment, then maybe you just deserve to get through this difficult period to go.”
Keane also gave his verdict on the form and future of United's out-of-form Brazilian star Casemiro. He suggested his dismal performance against Palace should put an end to the experiment of playing the midfielder as a makeshift defender.
“Casemiro is the last player you would want to play as a centre-back against Palace,” he added.
“Some players have all the experience but don't show it at certain times. But look at the whole Manchester United squad: if you tell me one player, I wouldn't play as a centre-back against Palace, who did that.” something is going on at home, they scored five against West Ham recently, they beat Newcastle and they even scored two against City – Casemiro wouldn't be against them.
“I would play at center back against anyone other than Casemiro. When you get to 31 and 32, it's going to be a shock every time you play a really bad game. I was told by people that I was done at that level, but players can get through it if they play in their best position.
“I watched Casemiro last night and he was struggling but he didn't get any help from the other players. If your legs are struggling a bit, get people around you to help and that's where he needs to be.” I have done better with his experience.
“Crystal Palace were really into it and everyone looked at it and thought Palace away on Monday night was going to be a tough night and Casemiro was isolated. He became isolated through his own fault, because he didn't have people around him, and you have to take responsibility for that.
“I'm not saying he didn't have a shocker. Great players experience dips in self-confidence, but who will help them?
“This is a top class player and you look at the guys around him, people like Jonny Evans, who is a centre-back. That's his position! He's also got full-backs around him and sometimes you look at one of your team-mates. ” and think 'that's not going to happen to him today' and I forgive a player when he's having a hard time.
“But if he is also out of position against a team that has some good players who can pass people by even in the best years, the mistakes only become greater.
“My frustration was with the players around Casemiro – help him. Jonny is a centre-back and the full-backs just have to fit in.
“But when we talk about a team game, structure-this and structure-that, playing between the lines, that's all well and good, but when you play against it you need your teammates around you. There's the whole idea of playing on a team.
“Of all the players at Manchester United, including the reserves and the youth team, if I wasn't playing at center back against Crystal Palace as a player, the one I wouldn't be playing would be Aaron Wan-Bissaka or anyone else.