Penrith's slide from the top of the NRL ladder to fifth place and consecutive losses by St George Illawarra have strengthened calls for State of Origin to be played as back-to-back fixtures while the Telstra Premiership takes a break.

Familiarity - not fatigue - is the main reason the Dragons and Panthers have struggled during the Origin period, as their NSW and Queensland stars have been available for training on just a handful of occasions since the teams for the series opener were announced on Monday, May 28.

At that stage, Penrith and St George Illawarra were at the head of the competition ladder, with the Dragons surrendering the outright lead after losing their round 12 clash with the Panthers just two days earlier.

In the six weeks since, Origin stars Ben Hunt, Tyson Frizell, Paul Vaughan, Jack de Belin and Tariq Sims have attended Dragons training just five times, and four of those sessions were captain's runs the day before a game. Each of those sessions comprised of 30 minutes of light running, with little defensive work.

It is a similar story at Penrith, who have lost three of their five matches in the six weeks since Nathan Cleary, James Maloney, Tyrone Peachey and Reagan Campbell-Gillard were chosen in the Blues team for Origin I.

St George Illawarra have lost their past two matches to Melbourne and Wests Tigers after two-point wins over bottom of the table Parramatta and Canterbury, and a 32-8 defeat of Manly in round 15.

Origin stars Ben Hunt, Tyson Frizell, Paul Vaughan, Jack de Belin and Tariq Sims have attended Dragons training just five times in the last six weeks

In comparison, Melbourne have come through the Origin period without losing a match for the first time in the club's 20-year history and are now second. There is no doubt the Storm benefited from Cameron Smith's sudden representative retirement.

South Sydney, who had four players involved in Origin this season, also won all five of their matches. On Saturday they claimed the outright lead of the competition after recording a ninth consecutive with a 24-6 defeat of the Bulldogs.

While many believe the main impact of high Origin representation on clubs is the fatigue suffered by the Blues and Maroons players, coaches complain about the disruption to their preparation for matches.

The Dragons are a team whose rise this season was built around extensive repetition and practice, along with the familiarity of a squad which barely changed until Origin.

None of their players spent excessive time on the field in Origin III, with Frizell and Hunt each playing 50 minutes, Sims and de Belin getting 34 and 33 minutes respectively off the interchange bench and Vaughan receiving a 25 minute stint at the start of the match.

However, with their halfback and four of the starting forward pack absent from training for an extended period, St George Illawarra have looked disjointed and been relying on individual performances in recent weeks.

So far this season, St George Illawarra coach Paul McGregor has used just 23 players in 17 matches, including five rookies who played in the 52-30 loss to the Storm. That places them alongside Canberra, who have also used just 23 players, as the club's to have made the lowest number of changes.

Of the other teams in the top eight, the Rabbitohs have used 24 players, while the Panthers, Sharks, Warriors and Broncos have each used 27 players and the Storm and Roosters have used 28.

McGregor rubbishes talk of Origin hangover

Significantly, Penrith recorded a 36-4 win over the Warriors and the Broncos thrashed the Titans 34-0 in round 17 after preparing to play without their Origin stars. Both teams suffered defeats last weekend.

Roosters coach Trent Robinson decided to rest his NSW stars Boyd Cordner, James Tedesco and Latrell Mitchell, as well as Cooper Cronk, from Sunday night’s match against Gold Coast and blooded the rookies – Sean O'Sullivan, Paul Momirovski, Matt Ikuvalu and Poasa Faamausili - who had been training in their places.

O'Sullivan, Momirovski and Faamausili scored tries as the Roosters triumphed 20-12 to leapfrog the Panthers into the top four.

Robinson supports Brisbane coach Wayne Bennett's plan to establish June as State of Origin month and play the series as back-to-back games, with 10-day break between each.

The Roosters mentor recently suggested the Telstra Premiership be reduced to 20 rounds, with no NRL matches played during the Origin period – a concept also backed by Penrith General Manager Phil Gould.

It is likely Dragons coach Paul McGregor would also support Origin being confined to a period free of NRL matches to minimise the disruption to teams.

The views in this article do not necessarily express the opinions of the NRL, ARLC, NRL clubs or state associations.