Defender Titus Bramble has accused Sunderland manager Paolo Di Canio of being a "strange person" and has told the Italian he has a lot to learn about dealing with players.
Di Canio arrived at the Stadium of Light on a rescue mission in April and, despite achieving his goal of Premier League survival, ruffled plenty of feathers with his outspoken approach.
He said that some of his players were "ignorant and arrogant" and admitted he had been handing out fines to a lot of his squad for breaches of his disciplinary code.
Striker Connor Wickham was also compared to a "playboy model" and, while some on the outside may enjoy Di Canio's candour, Bramble says it has not gone down so well inside the Sunderland dressing room.
Bramble, whose contract with the Black Cats expires this month, told the Daily Telegraph: "I've never played under anyone like him and I've played for some of the best managers around. Steve Bruce, Roberto Martinez and Sir Bobby Robson. He thinks he knows everything, but he has got a lot to learn.
"He's got a long, long way to go before he gets anywhere near as good as Sir Bobby Robson. He's a young manager trying to stamp his mark on things, but he's making some big mistakes.
"He's targeted the easy players, the ones who are leaving anyway, trying to show he's the boss. I was fined for not going to a weights session. Everyone else at the club thought it was ridiculous, but he's trying to be tough.
"He comes out in the media and hammers players and he hasn't said a word to them.
"He's never said anything like that to his (Wickham's) face. He's 19 and the manager is battering him in the media."
When Di Canio was initially appointed the debates surrounding him were over his political preferences given his previous statements he was a fascist - something he later denied.
For Bramble, though, his attitude to players was the only problem he encountered.
"He's a good coach on the training pitch," he added.
"Everything is so detailed. He's one of the best I've played for in that respect, but his man management skills need a lot of work.
"I never got any impression he was racist. From what I saw of him, he doesn't care about a player's colour or creed.
"Obviously, we were aware of the fascism thing, and the pictures of him doing the salute in Italy, but I've always refused to prejudge anyone and he never gave any indication he held those sorts of views."