After weeks of questions around his role in the halves, Hynes scored twice and engineered Cronulla's two other tries at Shark Park on Friday night.
The win came at a crucial time for Cronulla, snapping a run of four losses in five games and putting them back in the NRL's top eight in place of the Dolphins.
It didn't come easy, after the Sharks led 14-0 with 15 minutes to play before the Dolphins crossed twice in four minutes to get it back to 14-12.
Toby Rudolf then produced a try-saving play to deny Jeremy Marshall-King on a kick chase, before Hynes sliced through the Dolphins defence to seal the match.
Another long ball for Sione Katoa gave the Sharks' for-and-against a boost on the siren, capping a big night for the Sharks halfback.
Hynes wasn't the only star of Cronulla's win.
Cameron McInnes played despite going to hospital with an infection on his chest on Friday morning, while Briton Nikora's partner gave birth earlier in the day.
Addin Fonua-Blake also turned out after attending his grandfather's funeral earlier on Friday, while Blayke Brailey was again great out of dummy-half.
But it has been Hynes under the heaviest spotlight, with Fitzgibbon rejecting calls to move his marquee man to fullback in the past month.
On Friday night, Hynes did his talking on the field.
He scored the Sharks' first by running it on the last and splitting two defenders.
Their next after the break also involved Hynes, when he put Nikora over the advantage line in the lead up to a Jesse Ramien four-pointer.
Fitzgibbon afterwards pointed to the commentary around Nathan Cleary out of State of Origin III as evidence critics were too harsh on halves, wanting to judge on every win or loss.
"If you don't win a game you get criticised, but the magnitude of that is amazing to me for the stars of our game. It's actually disappointing," Fitzgibbon said.
"Nicho has been through plenty of that, but it has been a lesson for him.
"I thought he was strong tonight. Didn't overdo everything, just kept it simple.
"It was nice for him to have a few moments. It will probably keep them quiet for a week, hopefully."
Fitzgibbon was happier with Cronulla's defence.
The Dolphins have been the attacking juggernaut of the NRL in recent months, averaging 45.6 points over their past five games and reaching 50 thrice.
At the same time the Sharks have been guilty of leaking points, letting in 164 points in the past fives games alone.
But on Friday night, the script was flipped as the Dolphins long list of outs caught up with them.
With regular five-eighth Kodi Nikorima out and Hamiso Tabuai-Fidow rested, Cronulla's forwards rushed young halfback Isaiya Katoa.
Katoa's only success came with 13 minutes to go, when he put Sean O'Sullivan through a hole and the five-eighth kicked for Max Feagai to score.
The Sharks' defence was breached again four minutes later when Farnworth broke into space from within his own half to make it 14-12.
"As a spine we're good enough to react on the go," Katoa said.
"I just thought we weren't good enough and I take ownership of that. Just to relieve a bit of pressure for my outside guys.
"I got caught a couple of times on last tackle just stuck with the ball.
"We just took a while to connect as a spine and finally get some shape on in the last 20 minutes."
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