The Warriors feasted on Moylan and Cronulla's left edge last Sunday, scoring six of eight tries down that side on their way to a comprehensive 44-12 win.
Fitzgibbon has been loyal to a core group of players all season, even after big losses to Melbourne and the Dolphins, but dropped Moylan and benched left centre Siosifa Talakai for Sunday's clash with Manly.
Substituted onto the left edge after Teig Wilton went down injured, co-captain Wade Graham has been rested to recover from a niggling toe injury.
"He's had a broken toe for a while and his training has suffered a little bit," Fitzgibbon said.
"We want to get some life back into him and get his leadership back out there when he's right."
Fitzgibbon has favoured Moylan as five-eighth over Braydon Trindall since taking the reins last season and inspiring a resurgence in Moylan in his first campaign.
But the coach said no one was safe at the selection table as the sixth-placed Sharks, who ran second last year, risk falling out of the top eight with more losses.
"We want to start shaping our consistency. It's basically a message on how important our defence is," Fitzgibbon said of dropping Moylan.
"Obviously we were disappointed with our defence last week and to be fair it's been quite inconsistent for most of the year.
"It's got to the point where change was required.
"(Moylan) was understanding of those inconsistencies and fronted up, accepted the decision and he's turned up and trained hard this week.
"He's aware of where he's at. Matty's working hard at it but he hasn't got to where him or myself are happy with."
Fitzgibbon would not assure Moylan or Graham of playing a role in Cronulla's run to the finals.
"You don't know," he said.
"At the moment the most important thing on our minds is Manly on Sunday."
With Wilton missing the rest of the season, Jesse Colquhoun comes onto the left edge for only his seventh NRL game and first start.
Also capable of playing in the middle, the 21-year-old trained as a second-rower in the pre-season before breaking his foot and missing the opening weeks of 2023.
Fitzgibbon believes Colquhoun is up to the challenge of starting on the beleaguered left edge this weekend, when he will mark up on the Sea Eagles' dangerous, though recently underachieving, Haumole Olakau'atu.
"He's basically been exclusively training there for us for most of the year," Fitzgibbon said.
"He gets an opportunity with Teig being injured there, he was the best solution."
