Sydney Roosters coach Trent Robinson has detailed his reasoning behind demoting halfback Sam Walker ahead of his side's Anzac Day clash with St George Illawarra.

Walker was a surprise omission from Robinsin's team sheet on Tuesday in what was a selection statement by the Chooks coach, who has looked to move the magnets in swapping Luke Keary to the No.7 jumper while Joey Manu shifts from the centres into five-eighth.

The decision comes as Robinson hopes Walker can rekindle his best brand of football in the NSW Cup, with the young halfback needing to take control of the game at the lower level and potentially regain confidence.

The 2021 Anzac Day medallist, Walker has proven to be a player of the future for the Chooks, starring in the absence of Keary across the past two seasons to also earn Dally M Rookie of the Year honours.

Speaking to News Corp, Robinson said Walker "responded well" to the selection call and has laid out the 20-year-old's path back to the senior side.

"I felt like he needed time to work on two things. I want him to run our system completely in reserve grade and free himself to find parts of his game that he has always had," Robinson said.

"I wanted him to go and rediscover that. The path to freedom is playing through your system.

"He has reacted really well and trained well this week.

"This is what we feel is best for Sam and his development and then for us."

A win on Tuesday over the Dragons could see the Roosters move to fifth on the NRL ladder after eight rounds, with Robinson's side currently placed one spot outside the finals frame with three wins and as many losses from their six games.

The Roosters and Dragons will go head-to-head at Allianz Stadium on Anzac Day at 4:05pm.