After making the move from Brighton this week, Pedro made his debut on Friday in Chelsea's Club World Cup quarterfinal win against Palmeiras.
Deeney played with Pedro at Watford and he told talkSPORT: "Joao brings an intensity - he is obviously an exceptional football player.
“The social media clips Chelsea have put out in training show him throwing his weight around already.
“He’s all or nothing,” he added. “I think the misconception of him is that he’s a troublemaker. He’s absolutely not that at all.
“He’s passionate, energetic and he wants to win. He wants to play every minute of every game.
"But I think at Chelsea now you’re going to see the real Joao Pedro, one that enjoys competition and one that believes he should be starting for Brazil.”
To mentality
Deeney continued: “I’ve seen this player since he was 18 years old and the mentality has not changed one bit.
“It’s always been, ‘I want to be the best and I want to be the new R9’.
"Whether he can be that is for everyone to decide. In the short term, it's all about how he gets there. He’s only 23 years of age.
"I think the business Chelsea have done this summer has been exceptional so far.”