It feels too early to start shouting this, so let's whisper it: it looks like South Africa are back. Perhaps not back to their absolute best and definitely not back to the team they were when they were No.1, but back in business.

This series win is not going to become the stuff of legend and there were times when it seemed like New Zealand cared it about it more - after all, it is New Zealand who have never won a series against South Africa - but it will become seen as the marker for when South Africa began anew.

Calling themselves a team in transition more than two years after the retirements of Graeme Smith and Jacques Kallis and four years after Mark Boucher's had become a crutch, and South Africa knew it. They had already transitioned but they did not like what they had transitioned into. They were a team stuck in a rut. They lost five out of eight Tests last summer, in their worst season since readmission, and were badly affected by injuries and uncertainty.

To solve those problems, they did not hold a training camp before the series. They sat around and talked.

A large group of members of the national squad and those who might be considered for selection in the next few years were summoned to a bonding and strategy session. They plotted what they have started to call their "new mission." They don't want to share all the details but they have revealed that part of the plan will be to play more aggressively.

In their first attempt at applying that, in Durban, it failed when over-eager batsmen gave their wickets away. In their second, at Centurion, they attacked with their traditional strength - the bowling - and it worked as well, if not better than it always has.

Dale Steyn, Vernon Philander and Kagiso Rabada have formed a formidable fast-bowling trio that offers everything from swing and seam movement to pace and bounce but those are only half the reason they are so dangerous. The other half is that they just don't let up. Philander is the one with the reputation for putting the ball in the same area and the moving it just enough to create uncertainty but Steyn and Rabada maintain the same intensity through long periods of time.

There is never a stage in a Steyn spell when a batsmen thinks he can relax. Even when he has been hit for a few runs, even at the end of the day, even when it seems one over can just meander into the next, Steyn runs in with blood on the brain. Just when you think he is out of your face, in steps Rabada. He does not intimidate in the same way - there are no eyes, no veins, no tattoos - there is just pace, a lot of it. Rabada averaged 142.6kph in the first innings, more than anyone else.

That is the big difference between the two sides. Even though New Zealand's quicks have many of the same qualities as South Africa's, they are not as regularly ruthless. In Tim Southee and Doug Bracewell, in particular, batsmen can rely on getting enough loose balls to be able to score off. Trent Boult's skill and Neil Wagner determination were stand-out aspects for New Zealand but they needed more discipline from the rest of their attack if they wanted to properly challenge the South African batsmen.

In Durban, New Zealand encountered a South African line-up coming in from the cold with some of its biggest names out of form, and cashed in on that. At Centurion, JP Duminy and Faf du Plessis hit their stride and were more difficult to dislodge. South Africa's second innings gave New Zealand a glimpse of what could have been but by then, they had conceded a massive lead and their focus had to shift to how their own line-up could put on an improved showing.

That was where New Zealand let themselves down most. Their line-up went from solid to soft in the space of two sub-Saharan African countries and it has as much to do with the quality of the opposition as it does with the weak spots in their current set-up.

At the top, Tom Latham could not replicate his form in Zimbabwe but it is Martin Guptill who will concern them most. Three years after making 1, 0 and 1 in his first three Test innings in South Africa, nothing had changed. Guptill still struggles against the moving ball and there is evidence of that everywhere. In the 59 times Guptill has been dismissed by fast bowlers, he has been caught by the wicketkeeper or in the slips 24 times.

That alone made the case for New Zealand to have tried Jeet Raval in Zimbabwe to see what he could do but they may not have wanted to use him in South Africa because it would add to their inexperience. WIth Henry Nicholls at No.5 and Mitchell Santner batting as high as No.7, there was the risk of an over-reliance on Kane Williamson and Ross Taylor. When neither fired, New Zealand could not sustain their flickers of promise.

The difference came down to that: South Africa had more experience and more quality and even New Zealand's best efforts at preparation could not overcome those things. Rightfully, South Africa displaced them from fifth on the rankings to occupy the spot themselves.

It will be another eight weeks before South Africa are able to build on the gains they have made and they will have to do so in someone else's backyard. A three-Test tour of Australia in November is their next assignment, before they host Sri Lanka and travel to New Zealand. That gives them nine more Tests before Russell Domingo's contract as head coach is up and enough opportunity to climb even higher. It is too early to say whether it will keep him his job but the noise that he was the reason for their decline and could not possibly oversee their rise will become whispers.

South Africa's under-fire coach kept a low profile all series, even on the day they won. It was the same day he turned 42. At least he had a happy birthday.