Manchester United shouldn't have rushed to re-sign Cristiano Ronaldo, says former midfielder Kleberson.
The Portuguese made a high-profile return to Old Trafford in the summer from Juventus.
But since the £12.8 million transfer, the 36-year-old has endured a challenging season.
Ole Gunnar Solskjaer got the boot in November and the Red Devils have failed to mount a title push.
Ronaldo has bagged 14 in all competitions and is the club's top goalscorer this term. But ex-United and Brazil international Kleberson reckons his former club might have dropped a clanger bringing him back.
"To be honest, the Ronaldo experiment has been a bit of a failure so far - especially because of the level of player he is and how of late he has impacted the team," he said.
"When you look at the things he can bring to the club and what he brings to the fans, it’s not been amazing.
"The current United team haven’t played well together of late.
"It’s a tough time for Ronaldo to have returned to the club. Both him and United have a huge history together.
“Players like Ronaldo come back to a club after time away and it’s a totally different style of play and atmosphere to what they remember before. The club isn’t the same as under Sir Alex Ferguson and it must be challenging for him to comprehend that."
Ralph Rangnick is in interim charge at United until the end of this season. He will then take on a consultancy role for two years.
The 54-year-old oversaw considerable success with Red Bull Salzburg and RB Leipzig as director of football.
Leipzig bagged a second-place Bundesliga finish in 2017 and reached the Champions League semi final in 2020. Salzburg, meanwhile, have been a dominant force in Austrian football over the last decade.
Kleberson believes some tough decisions must be taken in the summer.
"The level of their current squad is high, many of the players have a lot of quality," he added.
"They are great technical players, but something is going wrong - this team needs a refresh.
"United have a lot of young players in their squad, but they need to just think more about who is going to take charge in this team.
"Who can and will motivate them? Who will organise this squad and get things going in the right direction?
"If you see the current players their club has, they can be performing much, much better if the team just gets on the same page. They need more fluidity.”