Roosters coach Trent Robinson says the advantage lies with strong attacking side, not stoic defensive setups in this year’s NRL final series.

The chief architect of the NRL’s greatest ever defensive structure says the significant advantages granted to offences under the game’s altered rules in 2014 are behind the massive momentum swings and high-scoring games in this season’s final series.

Last year, in Trent Robinson’s first season as an NRL coach, the Sydney Roosters set a new defensive benchmark on their way to premiership glory.

On the back of a defence dubbed “the Bondi Wall” the Tricolours managed a record six shutouts of opposition sides on their way to a 26-18 grand final win over Manly and their 13th first grade title.

But this year their efforts without the ball haven’t been as impressive, as evidenced by Saturday’s epic 31-30 semi-final win over North Queensland at Allianz Stadium on Friday.

The world club champions led 30-0 after half an hour before the Cowboys tied up the scores, only for Roosters playmaker James Maloney to land a late field goal to claim the win.

South Sydney’s 40-24 qualifying win over Manly two weeks ago also swung wildly, with the Rabbitohs racing out to a 40-0 before the Sea Eagles clawed their way back late.

In Saturday’s other semi-final encounter at Allianz Stadium, Canterbury led 16-0 and Manly fought back to even keel before the Bulldogs triumphed 18-17 in golden point extra time.

The Roosters 4-0 win over Manly in last year’s qualifying final seems a lifetime ago, given this year’s playoff scorelines and Robinson said the reason lay behind tweaks to the game’s laws introduced at the start of the season.

Those laws were aimed at creating more time with the Steeden in play and included introducing a seven tackle set for balls kicked dead, less scrums and increased opportunities for quick taps.

“You’ve got to think about it because it has happened in a lot of games this year,” Robinson said.

“The attacking advantage that’s happened in the rule changes this year and some tweaks to that, has given room for larger momentum changes.

“So as soon as a team gets an advantage, they’ve got better advantage through refereeing interpretations and some rules, and it’s hard for teams to right that when they’re under pressure, especially under (the) pressure of this time of the season.

“That’s a huge part of it, then it’s down to some quality players.

“We had a fairly good player in the opposition (Cowboys halfback Johnathan Thurston) that game for them and we couldn’t hold him.

“But I’d like to think it’s a lot more in the attacking hands than what it has been in the defensive hands.”