A verbal barrage from Josh Schuster in Manly's tight loss to South Sydney has convinced Brad Parker the Sea Eagles have made the right call in entrusting the youngster with the coveted five-eighth spot.

But by his own admission, Schuster's best is yet to come as Manly target a resurgence under new coach Anthony Seibold.

The Sea Eagles moved club great Kieran Foran on at the end of 2022 in part so Schuster could transition from the second row to five-eighth, the position he grew up playing.

Schuster has played two games as the club's full-time No.6 this season, setting up three tries against Parramatta, then putting in a solid showing during the 13-12 loss to Souths.

On Monday afternoon, Manly confirmed centre Tolu Koula had suffered a medial collateral ligament injury in the Souths game and would miss four to six matches after undergoing surgery on Tuesday.

Schuster is known for his slick ball-handling and running game but Parker, who plays centre on the same edge, said it wasn't until Schuster fired up at him in the Rabbitohs loss that his teammate won him over.

Usually one of Manly's most consistent, Parker had an off night against Souths.

He blew the Sea Eagles' captain's challenge by knocking on, missed a tackle on Cody Walker that led to the Rabbitohs' second try and threw a debatable forward pass that denied Manly a match-winner.

NRL football boss Graham Annesley later conceded the referee had made the wrong call on Parker's pass and that the ensuing try should have counted.

"(Schuster) actually gave me a spray on the weekend," Parker said.

"I'm happy with that.

"He's obviously a massive talent in attack.

"It's just the little details that he probably needs to start working on and getting better at.

"I'm starting to see it now. I'm really impressed."

Barking orders doesn't come naturally to Schuster, but it's more just than in that area that he is targeting improvement.

"I'm not much of a big talker so that's probably one of the main things I need to work in, is organising my edge, our attack," he said.

"I'm still new to the NRL, still learning.

"I'm still getting my match fitness right."

Schuster withdrew from consideration for Samoa's World Cup squad at the end of last year to spend the summer limbering up to play five-eighth.

Samoa became the biggest success story of the tournament as the first side outside of Australia, New Zealand or England/Great Britain to reach the final since 1968.

But with an uninterrupted pre-season at five-eighth under his belt, Schuster said he had no regrets staying home.

"To sacrifice a World Cup was a big thing for a young guy like me, especially someone who holds their country close to their heart," he said.

"If I look back on it now, it's probably the best decision I've made.

"I'm just so happy that I've got the opportunity now so I can show people what I'm capable of doing."