A recent report in the Sydney Morning Herald on NRL injuries showed the South Sydney Rabbitohs had collectively lost 180 playing weeks to injury this season, 60 weeks more than the next hardest hit team, the Sydney Roosters and more than double the average of all NRL teams.
While media pundits are proclaiming this as a terrible run of luck for the Rabbitohs, statistical analysis of these numbers strongly suggests that there is something other than bad luck at work here.
The mean (average) collective playing weeks missed through injury in the NRL this season is 84.24 weeks.
The standard deviation (a measure of how much a data sample varies from the mean) of all NRL teams in this report is 30.28 weeks.
The Rabbitohs’ 180 playing weeks missed due to injury is more than three standard deviations away from the mean of all NRL teams in this report.
A standard benchmark used in statistical analysis to judge whether an abnormal result is significant or not is for a result to be at least two standard deviations away from the mean.
The Rabbitohs’ result is 3.16 standard deviations away from the mean. This is a highly significant result and strongly suggests that something other than just bad luck has contributed to the result.
If we accept that the variation in collective playing weeks missed due to injury across all the NRL clubs is due to randomness (luck), and the amount of injuries is normally distributed (a bell curve, where most of the injury levels are clustered around the mean and minorities tapering out towards both ends of the curve), then the chance of the Rabbitohs 180 weeks missed due to injury being due to bad luck is 1 in 1,278, or just under a 0.08% chance.
This analysis on it’s own does not prove that something other than luck is causing the injury crisis at Souths (statistical significance does not prove causation and they could just be very unlucky).
But it does suggest that luck as the only cause of the injury crisis is improbable.
So what else could be contributing to the injury crisis at Souths?
Age of the squad doesn’t appear to be a factor. The average age of the Rabbitohs 2025 squad is 25.5 years. This compares favourably to the reported average age of NRL players in 2023 being 25.8 years old. The Warriors, who have the least injuries this season, have an average age of 25.7.
Wayne Bennett. (Photo by Mark Metcalfe/Getty Images)
Some fans have suggested that the move to the Heffron Park training centre was the cause of this injury crisis. But Souths sought an independent professional assessment of the Heffron Park training surface and it was given the all clear.
Other possibilities are the recruitment of players (recruiting players that other clubs let go because of injury concerns) or the management of training and injuries at Souths.
Without being on the inside and having a good knowledge of recruitment, training and injury management in the NRL, it’s impossible to know.
But it would be interesting to know if the same injury reports produced for previous seasons showed a trend of higher than average results for Souths (or not).
Now that Latrell Mitchell and Keaon Koloamatangi look like they are out for the season, South Sydney need to get to the bottom of why their team’s season has been ruined by so many injuries.
