In Hamilton he was scratching about – three runs off nine balls -- at a time when New Zealand should have been pushing on to victory. Ross Taylor, his 18th century completed, got himself out trying to push the pace. Santner was battling.
Then he got the idea. Seamer Tom Curran helped by serving up a full toss which was sent into the crowd at wide long on, and Santner was off.
Back to back sixes off spinner Adil Rashid, and another off quality seamer Chris Woakes to win the game in the final over gave him 42 runs off his last 18 balls.
That produced an understated fist pump from the languid lefthander. A strutting Shahid Afridi poseur Santner is not.
At the Mount, he got his first ODI half century and amid a mix of squirts and slaps, there were quality shots which suggest he may have crossed an invisible line with his batting this week.
"I'm striking it not so bad at the moment and it was nice to get the boys home in Hamilton," Santner said.
"Yesterday (Mount Maunganui) was about trying to get us a score which we could try and (work with). So things I've been working on are paying off and it was nice to contribute with the bat."
Santner has 58 wickets at 32 apiece and sits No 9 in world ODI rankings. He is an integral part of New Zealand's bowling lineup; now the batting is hinting that it's stepping up too.
"Of late I have been struggling with the bat. I think the bowling has been coming along a bit better than the batting.
"So it's good knowing you can still clear the fence if need be, and yesterday I spent a good time in the middle, something you don't often get to at No 8."
Santner may be no Ben Stokes, but he can fulfill a similar role in the sense of being a frontline bowler and a valuable middle order batting figure.
Stokes showed his importance to England at Mount Maunganui – and what his absence has left them covering. His contribution – two wickets, two runs and an unbeaten 63 – was substantial.
"He strengthens both sides," Santner said of Stokes.
"They've got a lot of bowling options and him at No 5 adds more depth. You've got David Willey coming in at No 9 so they bat very deep.
"Credit to the way they play. Even if you lose a couple of wickets early they will still keep coming hard because they've got reserves in the tank."
Santner could have been describing what the New Zealand team would like to see him develop into - providing middle order batting heft to either compensate if things go wrong early in an innings, or press on to take advantage of a strong situation.
You never know; in time this week may prove to be a watershed period in Santner's international batting development.