Coach Tana Umaga said Fai'ilagi had been through the mill since his first season.
"He had a year of injury last year that was a test to him. He probably didn't prepare as best he could returning from his breakout year.
"This year, I've seen a different Miracle. We asked him to up his game around his role.
"We know that he's good with the ball in hand, and we know what he can do.
"But I saw other stuff too. As a six [blindside flanker], he's really stepped up around his defence, his physicality, and he's getting better and better."
Umaga said that Fai'ilagi and another outstanding performer on the day, first five-eighths Patrick Pellegrino, had worked harder than he had seen them work before in their pre-season.
Part of the reason for that was the arrival of captain and All Black Ardie Savea with the side. As a result, Fai'ilagi was going from strength to strength under the example Savea sets.
"Ardie's lifted our standards throughout our team, and that's what we wanted, and what he has done. He leads through his action on and off the field."
Startling wing Kyren Taumoefolau was another who had benefited from Savea's example.
Umaga said, "Kyren is another one of these young players who has stepped up. It's good to have some pace on the wing. You can't teach that stuff.
"Kyren's been a bit of a standout these last few weeks. But again, he's taken to what it takes to become a real pro, and he wants to get better. That's great to watch from such a young man."
It hadn't been a perfect game from him, but he was still young, and there were small errors that were not fatal.
"He'll get better from that as he's always going to improve every week. We're really impressed with him."
With their win, Moana Pasifika set a standard for when they return from the bye, and they want to keep improving.
"It was also great to see the Drua getting up on the Chiefs. The Pacific Islands are doing well, and it's great when you have Super Rugby Pacific and the Pacific teams are winning.
"It makes it feel good for all our people out there. But we don't want it to be just now and then. We want to be consistent, so there is work for us to do."