Speaking to Betting.Betfair.com, Rivaldo said: "Casemiro is a great person, a friend of mine and someone I played with when I was at Sao Paulo. He had an amazing career at Real Madrid. In my opinion, it was the wrong decision for him to leave Real Madrid for Manchester United.
"I think he was living a beautiful story at Real Madrid, but of course, the financial side of things helped his decision.
"Manchester United are in a terrible moment, with so many injuries and Casemiro is a midfield player, not a striker or defender, so people criticise him playing out of position, but in my opinion, he is not to blame at all, because Manchester United are struggling massively on their own."