It's amazing how a couple of weeks can change things.

A couple of weeks ago, after defeat in Pretoria, it seemed England had forgotten how to bat time, had few spin options and little idea how to strike with the Kookaburra ball.

Now? Well, you still suspect that, were this England side to arrive in Australia for an Ashes series tomorrow, they would struggle. Maybe they still will in 22 months. But it feels as if they are, at least, heading in the right direction.

The basic statistics are these: an England team that has struggled to claim wickets in overseas Tests has now claimed 20 in three games in succession. An England side that has struggled to build substantial totals has now scored 391 for 8 and 499 for 9 in successive innings, while an England side that has struggled to win away from home has now won successive Tests in South Africa for the first time since 1956. And they've won an overseas Test by an innings for the first time since January 2011, too. These are significant achievements. They deserve credit for them.

There are two key factors at the heart of this resurgence and, to some extent, the new coach, Chris Silverwood, deserves credit for them both. The first is the very obvious change of approach with the bat; an acceptance that all that talk of positivity and aggression that accompanied the previous regime's efforts to build a Test side was naïve. This side, with Dom Sibley setting the tone at the top of the order, is much more inclined to take the old-fashioned approach to innings building: slow and steady, with an acceptance that the middle-order can accelerate far more easily if the shine has been taken off the ball and the bowlers are into their fourth or fifth spells. They are all the better for it.

The second factor is the decision to trust young players. Four men aged under 25 have either scored a century (Ollie Pope and Sibley) or taken a five-wicket haul (Jofra Archer and Dom Bess) in this series to date. A couple of others, Sam Curran and Zak Crawley, have contributed important performances. In Pope and Archer, in particular, you would think England have found players who will represent them for years to come.

This influx of new faces has had a secondary benefit. It has also challenged the more experienced players - the likes of Jos Buttler, Moeen Ali and Jonny Bairstow - to work harder to improve if they are to extend their Test careers. It has freshened up an England side which sometimes looked just a little cosy.

Certainly the middle-order - from Joe Root at No. 4 to Ollie Pope at No. 6 - now looks strong and settled. You suspect Jos Buttler may need an outstanding Test at Jo'burg to prevent a change at No. 7 - there appears to be every chance that Ben Foakes could win a recall for Sri Lanka with Buttler's future in white-ball cricket, perhaps as ODI captain - while Joe Denly needs a significant score to retain that No. 3 position. Bairstow made a century from there in England's most recent Test in Sri Lanka, after all.

Selection for that Sri Lanka tour will be intriguing. It seems, at this stage, as if England will rest several of their specialist seamers - including James Anderson and Stuart Broad - and leave the seam bowling in the hands of all-rounders such as Chris Woakes, Ben Stokes and Sam Curran. And while Dom Bess and Jack Leach, if fit, are assured of two of the spin positions, there are still decisions to be made about the other spot. Moeen Ali, at his best, probably still represents the best option England have - even though he, like Root and Bess, is an off-spinner - but Liam Dawson may come into the equation, too. Suffice to say, there are still issues with the development of spin bowling in England.

We do have to acknowledge the modesty of this South Africa side, though. The weak state of the economy has led to a mass exodus of players from the country and, as a result, the international team looks as poor as at any time since readmission. And you could argue the words 'since readmission' are generous.

There are no easy solutions to such challenges, but it might make sense to look at the costs associated with the Mzansi Super League - which isn't especially super - and instead divert some of that money to better pay for players. One or two of those Kolpak refugees might well be ripe for return if South Africa can match their earnings in England or New Zealand or wherever else they may have flown. Either way, we have to accept this result has been achieved against a side in a state of something approaching crisis. Tougher opponents, much tougher opponents, lie ahead.

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None of that need concern England right now. Just as Australia or India or West Indies rarely paused for pity of poor England sides, it is now their turn to be ruthless. It felt as if the Stokes-Pope partnership was the tipping point of the series; the moment South Africa knew they were beaten. England have a great chance to seal this series in Jo'burg where South Africa will be weakened further by the absence of Kagiso Rabada and England may well be boosted by the return of Archer, possibly in place of the spin of Bess. An attack containing Archer and Mark Wood on one of the fastest pitches in world cricket is an attractive prospect for a team who have been crying out for a fast bowler for years. Suddenly they have two.

Whether either man is available remains uncertain. Archer is bowling again in training but is not back to full pace while Wood last played back-to-back Tests in July 2017. He finished the second of them with none for a hundred and plenty. And if you had any doubt about the amount required of fast bowlers in these matches, just consider these statistics: Wood ran 38 km during this Test; that's just under 24 miles. While his top speed was 30kph - somewhere approaching 19mph - he exceeded 25kph in 167 separate sprints and 3.4km was run at a speed of over 20kph. That's beyond the maximum speed of most treadmills. The scheduling of back-to-back Tests is brutal and no doubt compromises the quality of fast bowling.

On the subject of scheduling and administrative decisions, this was another Test that underlined the value of five-day Test cricket. Had this been a four-day game, the weather would have had the final word. Not for the first time, the thought occurred that those charged with a duty to protect and nurture the game's future - in England, at least - are those most obsessed with embracing commercialism to the exclusion of other considerations.

This England team will not worry about that. Not now, anyway. Many of them are still fresh to these experiences and are relishing every new challenge. Nobody is claiming they are anywhere near the finished article but they now have almost a year until the India tour and almost two years until the Ashes. They have something to work with and time to improve. Those might be the green shoots of recovery peeking through.

George Dobell is a senior correspondent at ESPNcricinfo