But former Australia coach Deans, once a mentor of Carter's at the Crusaders, said the record-breaking No 10 must be backed to reach his former level.
"He can be a point of difference [at the World Cup], there's no doubt," Deans said yesterday. "That's why they're giving him that time. And I'd be confident he can get that job done.
"He doesn't fail at many things he sets his mind to. He's a bit like Richie, he could take it to another level, and in doing that, I'm not talking about him as an individual, I'm talking about his influence on the whole group because that's what great players do.
"He is still the highest scoring international in the history of the game. He's not doing too bad. He's had some challenges.
"That's the nature of the backs. The speed, they're more vulnerable to the soft tissue [injuries] and believe it or not the impacts as well because they're travelling faster."
Deans was in Auckland to promote his book Robbie Deans: Red, Black and Gold days after his successor at the Wallabies, Ewen McKenzie, resigned following the fallout from the Kurtley Beale text scandal.