The NRL has got its groove back, with data showing the league has ended three years of predictability and returned to the level of upsets that highlighted the best years of last decade.

And in a boost for the league coming out of the COVID-period, the opening 10 rounds have been the closest of any year in the NRL-era, dating back to 1998.

For so long promoted as the competition in which any side can beat any other on its day, the NRL lost that reputation badly in recent seasons.

Clubs were unable to sell hope to their fans, with data from the TAB showing that in the first three years of the six-again era - between 2020 and 2022 - the favourites won 74.5 per cent of matches.

The 2021 season best exemplified that, with a clear breakaway pack emerging early and favourites taking out 76.6 per cent of games.

But this year, the NRL is once again a tipster's nightmare.

The number of favourites winning has shrunk considerably, to 61.9 per cent over the opening 10 rounds, making for an average of three upsets each weekend.

That figure puts it close to on par with 2018 and 2015, and well above any other season from the last decade.

The NRL's head of football Graham Annesley believes part of the reason is teams better adapting to the significant rule changes of recent years.

"Those changes have helped with the flow of the game," Annesley told AAP.

"We made a deliberate strategy over the past two years to introduce a period of stability.

"This year we didn't make any real rule changes, we just made a few modifications to interpretations.

"When we went through that period after COVID with six-again rules, we knew some clubs would adapt faster than others.

"What we have seen over the past 12-18 months is teams have been playing catch up on that, and to a large degree have now caught up."

Other potential impacts have included the introduction of the Dolphins further spreading out talent under the salary cap, and top teams being impacted more significantly by last year's World Cup.

Only one win separates third from third-last on the ladder, with lowly Canterbury having recorded four victories and third-placed Penrith five.

At this point last year, the gap between third and 14th was four wins. In 2021 it was six.

Never in the NRL-era has it been this close.

The average margin in games sits at 11.2 points, while more games (54 of 80) have been decided by 12 points or fewer than in any other season at this point since 1998.

That figure is well improved on the blowout days of 2021, when the average margin was 18 in the first 10 rounds, and only 33 games were decided by 12 or fewer.

"A lot of teams are hot and cold," Sydney Roosters star James Tedesco said.

"Teams are just a bit more even this year and competitive. It's not really a big difference between the top teams and bottom teams.

"Each week, anyone can win. Cowboys have got a great team, have played some great footy but are still down the bottom of the table."

PERCENTAGE OF NRL GAMES WON BY FAVOURITES

2023: 61.87

2022: 72.64

2021: 76.61

2020: 74.26

2019: 66.42

2018: 61.69

2017: 66.17

2016: 70.15

2015: 60.95

2014: 62.69

2013: 68.16

2012: 64.93

2011: 67.91

Source: TAB