The former Manchester United defender has been hugely impressed by Rudiger's performances since Thomas Tuchel took charge at the start of this year.
The German centre-back faced an uncertain future at the club when Frank Lampard was manager and Ferdinand admitted his confidence would have 'taken a beating'.
But Rudiger has bounced back and become an influential figure for Chelsea over the last nine months and scored in their 3-0 rout of London rivals Tottenham at the weekend.
Ferdinand was effusive in his praise for the Chelsea man after that victory and said on his YouTube channel: 'Since Tuchel has come I think he's arguably been the best centre-back. I think him and Dias would have been close but the effect he has had on his team has been immense.
'Under Frank [Lampard] , it was evident he wasn't Frank's cup of tea. He didn't really like him. There were rumours they were trying to put him in the market to be sold.
'In Germany, he's always been highly thought of. But when the manager doesn't rate you and you can feel that, I don't care who you are your confidence takes a beating and it's hard to perform at that level.'
Rudiger, who is now one of the first names on the team sheets, however finds himself in a sticky situation with just one year remaining on his contract and no agreement in place to extend it.
Paris Saint-Germain and Real Madrid are already circling in anticipation of signing him on a free transfer at the end of the season but Tuchel is desperate to tie the defender down to new long-term deal before he can talk to foreign clubs in January.
'I hope that they find solutions, but it's not only between coaches and players, and what we wish for and that's why it's between the club, the players and the agent at the moment,' the Chelsea boss said.
'We hope that they find the solution and everything I can say, he plays excellent, and since a long time very consistent, on a very high level.
'I feel him very calm and focused, and it's not a distraction for him. So everything is in place, and give things the time they need. Sometimes it needs a bit longer, sometimes things are very fast.
'There's no news from my side, and I think that Toni feels very, very good at Chelsea, he feels very respected by his team-mates and he feels the importance that he has in the team and in the squad.
'That's well deserved because he delivers, he feels the love from the supporters when he plays. He's in the strongest league in Europe, in a big club, so not many reasons to change that.'