In Kagiso Rabada's dip is the story of South Africa's decline in Tests

The blame for South Africa's Test decline has been laid at the feet of the batters, who have collectively crossed 300 just twice in their last 15 innings, and have often left the bowlers with too little to work with. While that's correct, it doesn't adequately express how deeply the dearth of runs have blunted the team's strongest suit - the seamers. And to see how deep the impact has been on the bowling, one needs only look at Kagiso Rabada's last three years.

Rabada is the undisputed leader of South Africa's attack. Since his debut in November 2015, no one has taken more wickets for the team than Rabada, and the next best, Keshav Maharaj, is more than 80 strikes adrift. That in itself says something about the changing styles of success in South Africa's bowling.

Not too long ago, having a spinner among the top-two wicket-takers would have been unthinkable. But with several series in the subcontinent over the last six years, Maharaj has been able to do much more than keep an end quiet. But that raises all sorts of questions about the pace pack South Africa put on the park and whether they are providing enough support to Rabada.

Look at the list again. The next most successful quick since Rabada's debut is the now-retired Vernon Philander, who took 101 wickets in 61 innings between 2015 and 2020. He opened the bowling alongside Rabada in 17 of those and, as the table below shows, maintained a great economy rate and still struck regularly, allowing Rabada to reap even greater rewards at the other end.

Philander was not always able to partner Rabada, though. He suffered an ankle injury in India in 2015, missed matches in Sri Lanka, and had fitness concerns on a tour of England in 2017. In his absence, Rabada has had a revolving door of new-ball partners, ranging from Morne Morkel to Duanne Olivier to Kyle Abbott to Lungi Ngidi; and none of them have done as well as Philander.

When Rabada has opened the bowling with anyone else, the opposition's scoring rate has been higher. As the numbers below show, while Rabada has stepped up in those situations, he hasn't had the consistency of a bowler like Philander to back him up. That may be for a variety of reasons, including experience and skill. There are few bowlers with the ability to move the ball as subtly and effectively as Philander did, and fewer in the South African set-up with years under their belt to have perfected their craft. Philander had played first-class cricket for five years and 61 matches before his Test debut; Ngidi, as one example, had two years and 11 caps before his.

With Philander offering his services from the commentary box now and South Africa yet to find a replacement - the most likely candidate, Glenton Stuurman, has not been picked for the West Indies tour - the burden lies even greater on Rabada.

South Africa have not played a significant amount of Test cricket in the last 18 months to be able to minutely assess Rabada's form, but we can let the numbers do some of the talking. Rabada has slipped to their third spot among South Africa's Test wicket-takers since Mark Boucher became head coach - from December 2019. Anrich Nortje is No. 1. Nortje has taken double the number of wickets as Rabada, although he has played three more Tests. In that time, Rabada's average has crept up over 30 and he has not managed a five-wicket haul.

In fact, his last five-for came more than three years ago, against Australia in the Port Elizabeth Test of March 2018. South Africa won that series 3-1 but that was their last major achievement in Test cricket. Since then, they beat both Pakistan and Sri Lanka at home (which some would argue was expected at the time) but also lost to both those sides, Sri Lanka at home and Pakistan away, and to England. And the dip in South Africa's form has coincided with a downturn in Rabada's fortunes.

Though he has had to shoulder more of the responsibility since his last five-for - only Maharaj has bowled more balls in this period - Rabada's personal numbers have gone down too; although he remains South Africa's leading bowler and, compared to bowlers around the world who have played at least ten Tests, his strike rate sits sixth. He has taken 67 wickets in 17 Tests since the Port Elizabeth five-for at an average of 27.2, compared to 135 wickets in 20 matches before that, at 21.45.

At the same time, South Africa have gone from having the best bowling average in the world from Rabada's debut to the Port Elizabeth Test, to having the fourth-worst bowling average in the last two years. In that time, they have taken six five-wicket hauls,the fewest among the eight teams that have played at least ten Tests.

Clearly, South Africa need Rabada to be at his best for the attack as a whole to perform well. That probably means they have to avoid over-bowling him, as has sometimes been the case, and for their other seamers to find a collective consistency that allows Rabada to operate in fiery bursts for maximum impact.

South Africa's new Test captain Dean Elgar did not initially think the West Indies was the place to make pace a focus and said he was expecting slow, low pitches - this, even though the Caribbean has been good to fast bowling in the last few years.

Since then, South Africa have seen first-hand that the Dukes ball allows for damage to be done early on. During an intra-squad practice match, bowling coach Charl Langeveldt said the seamers could end up playing a big role in the two-match series, given the ball, and the weather, with high humidity in the rainy season contrasting with the dryness South Africa have experienced on previous tours. "With the Dukes ball, there is a lot of movement - seam movement off the wicket - and it stays harder for longer. Ball maintenance is key. Obviously we can't use saliva anymore, but we need to find a way to shine the ball and that could be beneficial for us."

Rabada has previously been effective at executing reverse-swing. If he finds some of that magic or manages to effect maximum damage with the new ball, South Africa can rekindle their reputation of being a team with a core of seamers as their strongest suit.