Bradman Best kept his place in Australia's centres for the final pool match against the Cook Islands, with Latrell Mitchell left out.
Walters had started Mitchell against New Zealand, then selected Best on the left for the remaining pool games.
Kotoni Staggs played right centre in all three matches, but his defence drew criticism and his combination with Tom Trbojevic had yet to click.
Former Kangaroos centre Josh Morris called Mitchell's continued omission "bizarre" and said he would have dropped Staggs instead.
"He (Best) has done enough to keep that position," Morris said on The Continuous Call Team.
"But on his day we know we know how devastating Latrell can be. "
Morris said he would have tried Best on the right against the Cook Islands to test his defence there.
"I thought against the Fiji side we conceded two easy tries down that right edge.
If I was looking at making a change I probably would have made it there."
Walters said Mitchell's absence reflected Best's form, rather than a problem with the South Sydney Rabbitohs centre.
Walters is due to name his side for the knockout match against Samoa on Tuesday, putting the centre selections in focus.