The All Blacks’ style of play focuses on shifting the ball quickly across the backline from side to side, patiently working the defence until they create an overlap or find space for a clean break. As a result, the forwards are constantly required to sprint from one side of the pitch to the other, so their conditioning prioritises endurance and mobility over raw gym-based power.
The Boks also have an aging pack which may also make this game plan less practical, and the bench has been useless this season so far.
One of the reasons the breakdown was so bad against Australia was the Boks were slow to get to the breakdown. Although this might also have been because the forwards were often out wide, and not committing enough numbers to the breakdown.
When Bongi got on, he looked tired after 10 minutes, and he has been dropped from the match day squad- perhaps for ever.
A player like Thomas DuToit has mobility and fitness, albeit not the strongest scrummager. Mostert is also a player that is very fit and mobile, even though he too is aging.
Lots of pundits are saying the Boks should go back to 10 man Bok rugby after one loss. It might just be knowing when to go wide and when to keep it tight- and also selecting forwards that can run more to support multiphase play - rather than just the tight phases.