That seems to be the prevailing view. But what are the facts? There were 5 knockout matches that were competitive, I leave out the Japanese hammering in 2019.
Wales 2019…..Kolisi was subbed in minute 69 when the score was 16 to 16. His absence ensured our win because Louw made the crucial turnover leading to the winning penalty. Final score 19/16. Score after Kolisi left 3/0.
England 2019….Kolisi subbed in minute 64. The Boks were ahead 18/12 and the match wasn’t won. Final score 32/12. Score after Kolisi left 14/0.
France 2023….Kolisi subbed in minute 46, the Boks were behind 19/22. The final score the Boks won 29/28. Score after Kolisi left 10/6.
England 2023….Kolisi subbed in minute 51. The score was Boks behind 6/12. Final score Boks win 16/15. Score after Kolisi left 10/3.
New Zealand ….Kolisi subbed in minute 73…the score 12/11 which was also the final score. In at least 3 of these games, Wales, France and England we won the match after he left the park.
In aggregate we were 71 /73 with Kolisi on the park and 37/9 after he left the park. Clearly there were other factors at play. For example Pollard coming on and making his kicks. But it’s very hard to argue Kolisi was essential to our WC wins. In every match the victory was in doubt when he left the park.
And in every match except NZ we did markedly better after he was subbed.
Kolisi leading us to WC victory is a pleasant fiction.