That much should have been obvious when the triumphant U-19 side returned home to be presented to fans at a Test match at Newlands. Their seniors were being flayed by a buoyant Australia - the seniors of the men Rabada had torn apart just a few days before - so the U-19s were a welcome distraction for South Africans looking for something to be cheerful about and Rabada an immediate hero. Even his team-mates thought so.
"Do you know he has a franchise contract lined up?" the likes of captain Aiden Markram, who was the team's top-scorer in the World Cup, and Corbin Bosch, the all-rounder who starred in the final, were whispering among each other, within earshot of the media.
"Does anyone else have a franchise contract they are discussing?" I remember asking. "No, just him," the bright-eyed boys said. They were obviously in awe.
So were the suits at the Johannesburg-based Lions franchise, who made sure they secured Rabada's signature before anyone else.
Ten days after Rabada was presented to the crowd at Newlands, he made his first-class debut for one of their provincial affiliates - the teams that feed into the franchise squads - Gauteng. He took 3 for 28 in the first innings and went wicketless in the second. The next week, he had a match return of 4 for 66. Neither performance was particularly spectacular, but the week after that, Rabada was promoted to the franchise side. Clearly, big things were expected of him.
"I knew about Kagiso from the time he was at school and I knew he was a player to keep a close eye on and I wanted him in my team," Geoffrey Toyana, the Lions coach, told ESPNcricinfo. "His reputation was that he was fast, so fast that he didn't take as many wickets as he should have at school level. He was actually too quick for the guys he was playing against - they couldn't even nick him off."
At professional level, the batsmen were more capable of handling the pace but equally flummoxed by Rabada's guile, which was remarkably well developed for a young man. "From the beginning, he had a lot of control but it's also something he really worked at," Toyana said. "He spent a lot of time at the Wanderers, in the nets, with (bowling coach) Gordon Parsons, with the other bowlers."
Rabada consumed cricket and it consumed him. Shortly after the domestic season ended, he was picked for the South Africa A squad to play in Australia and before that could even happen, was also included as a non-playing member of the national team, which went to a triangular series in Zimbabwe. In three months, Rabada had gone from schoolboy to sporting sensation.
When the next summer began and Rabada's U-19 team-mates were contemplating things like whether to begin tertiary education or whether they may be picked up by a provincial side, Radaba made his international debut in a T20 series against Australia. He only took one wicket in three matches but impressed Allan Donald, who was then South Africa's bowling coach and gave Rabada a glowing review.
"He is a young pup. He asks great questions. I am blown away by the knowledge he has got at 19," Donald said. "He wants it badly. He is a great athlete, he has got immaculate work ethic and he has got some gas. He is built like a race horse, a thoroughbred and that's exciting." Donald predicted Rabada's "time will come," but he didn't know how quickly the clock was ticking.
Rabada returned home to find himself a full-fledged member of Lions' pack and in his 10th first-class match, he became their leader. Against Dolphins, Rabada took a record off none other than the leader of South Africa's attack Dale Steyn. He claimed 5 for 72 in the first innings and 9 for 33 in the second, to finish with 14 for 105 - the best bowling figures in a first-class match in the franchise era. Steyn had produced 14 for 110 seven seasons earlier.
"What was so amazing about that performance was the way he kept coming back," Toyana said. "Sometimes when a bowler takes a five-for, he thinks his work is done and then he relaxes but after he did that in the first innings, he wanted more. He ran in hard in the second innings and just kept taking wickets."
But if anybody thought Rabada's best was on display that day, they were also wrong. The young man had better in him.
There were glimpses of it during the first T20 in Bangladesh, Rabada's first full international tour in which he features in the squad for every format. In conditions which are supposed to be tough for seamers, Rabada put on an impressive short-ball display and although he was expensive, his aggression would not have gone amiss. Still, he was not picked for the next match.
"Dropped" is not a word South Africa use too freely, "rotated" is more like it, but whatever it was, it seems Rabada does not want it to happen to him again. When picked for the first ODI, he made himself undroppable with a jaw-dropping performance that included only the second hat-trick on debut and the best figures by a bowler on ODI debut. Ever.
If anybody thinks Rabada's best was on display during his 6 for 16 in Dhaka on Friday, chances are they are wrong too. Who knows how much better is to come.
Firdose Moonda is ESPNcricinfo's South Africa correspondent