After Leinster's 41-19 Champions Cup final demolition by Bordeaux-Bègles, Victor Matfield has offered the most compelling explanation yet for why Nienaber's outside-in defensive system keeps failing at Leinster but thrived with the Springboks: raw physicality. Matfield's argument is simple — the Boks win the collision, slow the ball, and reset the defence. Leinster can't consistently do that, so quick ball and efficient rucking expose the system's high-risk architecture before the line is set. John Kirwan adds another layer, arguing the breakdown isn't just physical but psychological — that Leinster's players weren't fully committed to the press, pointing to Ioane's forward move going unsupported as evidence. The implication from both legends is damning: Nienaber's system isn't broken, it just requires a specific kind of team to execute it, and Leinster may simply not be that team.