Does having a positive set restart differential matter? – NRL Round 8 2020 stats and trends

Last round I noticed something interesting with set restarts. Round 7 marked the first time that set restarts, and net set restarts, had a negative correlation with final margin. This meant that the larger the gap between restarts awarded and conceded, the lower the margin was likely to be.

After Round 8, the trend has continued as the net restart versus margin chart shows below (the larger the circle the more set restarts awarded):

With five rounds 40 games completed, we’re moving out of the small sample size zone and these results start to have a bit more meaning. Still, it’s not a strong negative correlation between net set restarts and margin, but it’s worth exploring what is causing this this. Looking a bit deeper there’s two major things contributing to it.

The first is the Panthers being a complete anomaly. With a set restart differential of -20 they’re by far the worst in the league, with twice the infringements of the Titans. Penrith have four of the seven worst set restart differentials so far this season. They haven’t lost any of those games (three wins and the draw against Newcastle).

And the only game they did come out ahead in set restart differential, Round 5 against the Eels, they lost. In Round 6 they had a net set restart of -7 against Melbourne but won 21-14. They followed that up with a net set restart of -5 in their 20-12 win over Souths. It appears to be a deliberte part of their game plan to give them up and ensure their defensive line is set.

The other reason for this negative correlation can be seen from the chart below, showing each team with their net margin plotted against net set restarts:

The Roosters, Melbourne and Eels have the three highest net margins since Round 3 but are giving up as many set restarts as they’re receiving, with the Roosters having a set restart differential of 0.

On the other end of the spectrum, the Warriors, Dragons and Bulldogs are all ahead on set restart differential but are well in the bottom half of net margin after suffering some humiliating defeats.

Meanwhile the Broncos appear to be trying to game the system with a set restart differential of -2, but are clearly struggling with the setting your defensive line part of it having conceeded 139 more points than they’ve scored in the 5 rounds since the season restarted.

Much like completion rates, winning the set restart differential isn’t always reflected in the final score. As has been stated many times this season, the new rule system is just increasing the gap between the haves and the have nots. Set restarts are being gamed by the well coached teams and strategically giving them up looks to be part of the new rugby league meta.

Penalties and set restarts are reverting to the mean

Overall penalties and set restarts have continued to decline this round, around 8 per game, respectively. We’re back to averaging a set restart roughly every 3 sets of six, up from around 2.5 in Round 7.

The big difference this week was in the second half, which can be seen in the chart below. First halves total penalties were steady, but the difference came from second halves where there were 5 fewer penalties and 17 fewer set restarts.

The decrease in second half penalties isn’t new, as you can see it was occuring before the season shutdown in March, with two abnormal weeks for second half infringements (Rounds 5 and 7).

Who is calling set restarts?

Looking at the how the referees have been calling them, Chris Butler has followed the trend of Peter Gough calling a large number of infractions in his first game officiating this season.

Butler blew the pea out of the whistle this week with 12 restarts and 7 penalties in the Warriors game against the Broncos. That was only surpassed by the 16 penalties and 12 in the heated clash between the Tigers and Panthers that followed it on Saturday night. Both Gee and Butler are blowing double digit set restarts this season, the only referees to do so.

Interestingly Gough was a bit more restrained this week with only 13 total penalties (5 set restarts and 8 penalties).

Finally, it looks like the Suttons are the most likely to call for a penalty instead of a six again, as they are averaging over 11 penalties a game so far this season. Both are only calling seven restarts a game, which puts them in the bottom half of referees this season. Ben Cummings continues to be the stingiest with the whistle, with fewer than six set restarts a game.