The left arm spinner and left hand batsman has played 21 matches for his country. The mechanical engineering student at Waikato University would be the first to admit he's far from the finished product and yet there's aspects about his game which indicate he has a long international career in front of him.
An Adelaide double of 31 and 45 - second top, then top scorer in New Zealand's two innings of the day-night test - and a couple of wickets were achieved with a misleading laidback demeanour which remains intact.
Santner has suggested his body language is of the duck variety - calm on top, paddling furiously beneath the surface.
The nerves have certainly not entirely gone away, but they have eased. In any case having an edge on the eve of important games is no bad thing.
"You still get nervous every time you play for your country. It's a nerve-racking thing," Santner said.
"But once you've actually performed at that level it gives you a bit more confidence for the next game.
"It does settle the nerves a bit, knowing you have performed against good international teams."
Santner is also clocking up the lessons sport hands out to young athletes making their way.
Take his last two games on Eden Park.
Against Pakistan last Sunday, his five overs went for 56 as Mohammad Hafeez and Babar Azam clattered into him. On Wednesday night, his unbeaten 35 might have been important, had Australia not batted like proper Charlies when chasing 308. The innings was ended by Santner's first two deliveries of the match.
If you watch Santner in the field, he has the look of an athlete, a quick and sure mover and as a result has made the taking of several catches look easier than they were.
He's determined to stay an allrounder, rather than let one skill become the dominant part of his game. It's a tough gig but he's certainly got the potential.
Santner's hunch is that his batting has come on slightly more than his bowling of late.
"Our top order has been going really well so I haven't had too much chance to bat. But I'm just banking those experiences and working just as hard at training in both.
"I want to be contributing with both, and in the field. It's hard to manage both aspects. But I want that genuine allrounder spot."