He has soaked up the information from assistant coach Grant Henson, who wore the Steelers jersey on 101 occasions from hooker, and has benefitted from playing in between two strong scrummaging props in Jarrod Firth and Pauliasi Manu. Sua's own game has proven very consistent, especially in his core roles, and he has had the chance to show his speed, from his days on the wing as a junior, out wide as the Steelers like to use him.
"I thought if I had to work really hard for my spot it would really pick my game up," said the former NZ Schools player. He has also spent time with the Blues as injury cover (in 2013) but has yet to get on the playing field.
Sua is going to sign with the Steelers again for 2016 and he has the chance to cement that Steelers hooking role for some time to come. Since Henson hung the boots up in 2011, there have been several rakes used, among them Mark Price, Suliasi Taufalele, Mahonri Schwalger and Hika Elliot.
"I didn't know a lot about Gafa before he came here. He didn't get a lot of ITM Cup game time last year," said Henson. "From what I heard, fitness was an issue with him, but we had a good talk and told him to show us what he's got in club rugby. He's been outstanding in his core roles for us. He's sharp on defence, like another loose forward. We like to use hookers in that wide channel and he's got a bit of pace.
"Sometimes players just need that change of scenery. So his gamble's paid off," added Henson.
Could Sua be capable of playing Super Rugby in 2016? The Blues, after all, are losing Keven Mealamu to retirement. Henson says he could be a useful pick-up, even as a wider training group member somewhere.
"If they're looking for someone who performs their set-piece to the highest level and then offers plenty around the field, then he ticks all the right boxes."
Sua knows Saturday night's final game of the season, against Auckland in Pukekohe, is a chance to continue the momentum from the last three games, where the Steelers have collected the maximum 15 points and played with freedom minus the errors that bedevilled the first half of their campaign.
More than anyone, Sua knows how Auckland will still be smarting after last year's 41-18 hiding on the same ground. He came off the pine for the Auks that Wednesday night.
"It's a big game for them. They want that home semi, so they'll come out firing. They look at us as the little brothers.
"Our skill level (in the wet) against Waikato was good. It shows how confident the boys are and keen to attack."
Sua will likely match up against Greg Pleasants-Tate, another strong scrummager who has been in fine form for Auckland.