Santner tries on Vettori-sized shoes

Mitchell Santner was trusted with the new ball in the first ODI against South Africa in Hamilton AFP

A left-arm spinner who is a banker for his captain and a batsman who, while rarely pretty, can cobble together some handy runs was something New Zealand got used to for almost 20 years.

Daniel Vettori's retirement after the 2015 World Cup - in which he had the thriftiest economy rate for any regular spinner but where his most important contribution was the squirted four to third man in the final over of the semi-final against South Africa - left massive shoes to fill.

The job fell to Mitchell Santner, another product of Northern Districts, and he is now stepping into the breach with aplomb.

In the first three matches against South Africa, his economy rates have been 4.71, 4.60 and 4.50 and he has also chipped in with four wickets. Given the new ball in the first match in Hamilton, he ripped a couple past Hashim Amla in the opening over; in Christchurch he defeated JP Duminy with flight and in Wellington he removed the dangerous David Miller.

A particular feather in the cap is how he has bowled to AB de Villiers: 51 deliveries to him for just 41 runs. "When I'm bowling to him I just try to get dots when I can," Santner said, "but he's so good at rotating the strike against our good balls. Hopefully I can nick him off at some stage."

Santner is now shaping as a key figure in the second match on his home ground at Seddon Park - the rearranged fixture taken away from Napier - where New Zealand must win to set up a decider and keep an eight-series winning streak at home alive.

Though it may not spin to quite the extent of the opening match, where the pitch was affected by the wet weather, it is expected to take some turn. New Zealand have prepared for that by including offpsinner Jeetan Patel as a third frontline option in the squad, and alongside Kane Williamson they have a plethora of options.

Unless New Zealand make significant changes to the balance of their side - they are already going to have to reshuffle with Luke Ronchi set to take the gloves the from Tom Latham - it would be unlikely that all three specialists will play, but Santner said it would "pretty cool" if it were to happen.

"The last game here it spun quite a bit and even in Hagley it spun a bit," Santner said. "Hopefully there is similar stuff on Wednesday and there's a bit of turn. I need all the help I can get otherwise I go the journey."

While that last remark may have just been Santner's modesty, he does himself a disservice. His economy rate from 30 ODIs is 5.07 and though that is almost a run higher than Vettori finished on, in an era of escalating totals it is a notable effort. Five has become the new four for a bowler.

It was not the easiest of starts for Santner: in his first two ODIs he went for 137 in 15 overs against England in the slug-a-thon that was the 2015 series. But even before that series had ended he'd fought back, claiming his career-best 3 for 31 at Chester-le-Street.

Since those rocky first two outings, only three times has he gone for a run-a-ball or worse, and only once has he really been dispatched - when Pakistan clubbed him for 56 off five overs at Eden Park, a ground where a spinner has to know the short boundaries carry the risk of making it a hazardous occupation.

Like Vettori, there is another part of Santner's game that brings value to the side. But life is a bit trickier with the bat at the moment. Being stationed at Nos. 7 or 8, as Santner regularly is, will limit the opportunities for a substantial innings, but twice in this series - in Hamilton and Wellington - he has arrived with significant time remaining only to return 17 and 1.

In his first 11 ODI innings, he passed 40 three times but in his next 14 his top score is an unbeaten 38 - a vital innings against Australia in Hamilton. Santner said it was a challenge to devote as much as he would like to both his disciplines, although in Test cricket - without its scoring-rate pressure - his two highest scores (73 and 71) have come in the last six months.

"It's [batting] situation dependent. If you lose a few wicket early it's about rebuilding, but ideally at seven or eight you want to be coming in with a couple of overs left and having to hit from ball one," he said. "That's the nature of batting down there.

"In my position I want to be scoring runs and taking wickets and it is hard to manage both at the same time. My bowling has been okay lately, but ideally I would like some more runs."

There's plenty of time on Santner's side to marry his two skills together. After all, Vettori waited until the penultimate innings of his career to play his defining shot.