New South Wales coach Brad Fittler has conceded that the decision to overlook Josh Addo-Carr for State-of-Origin selection earlier this year may have been a mistake following a sublime World Cup performance.

"He was fantastic," Fittler said.

"What he did is he proved that he's the best person for that job. One thing that was really strong was his defence and he was carrying the ball out of trouble.

"He was one of the best players in the Australian team."

The Gunggandji, Birrbay and Wiradjuri man was one of the standouts at the tournament in England.

He crossed for 12 tries in just five starts for the Kangaroos, three better than leading English counterpart Dom Young.

Addo-Carr set the tone in Australia's World Cup opener against Fiji, quickly turning defence into attack in a 90-metre try that included sprinting up the sideline before stepping back infield to cross near the posts.

That try almost paled in comparison when the 27-year-old bolted nearly half of the length of the field in the semi-final to catch a 40-metre cross-field bomb to score against New Zealand.

Fittler argued that playing with Indigenous centres Latrell Mitchell and Jack Wighton, and other NRL stars James Tedesco, Valentine Holmes, Cameron Munster and Nathan Cleary feeding Addo-Carr the ball, was the difference.

Fittler preferred the form both Brian To'o at Penrith and Anthony Tupou from Sydney Roosters displayed on the wing over Addo-Carr playing for a struggling Canterbury.

"He was playing better in November than he was in March," Fittler said.

"I think if he takes that into the off-season and then playing for Canterbury (and) they have got a new couple of players, and all of a sudden, they could be winning games.

"It always helps when you're winning games, and he's going back to a club that in my eyes will win more games because it looks like they're going to be stronger.

"Everyone wants to see Josh play in the rep arena where you can see that he takes the game to another level."