Considered a frontrunner for the premiership this season, the Roosters were dismantled in the opening 40 minutes by a slick Eels outfit who bounced back emphatically from Monday's shock loss to Canterbury.

The Roosters, usually renowned for their stoic defence under coach Robinson, have conceded 146 points across their past six games.

Granted they lost brothers Egan and Nat Butcher to concussion and were without Luke Keary, Victor Radley and Jared Waerea-Hargreaves, but the Roosters (7-8) have won just once in their past five outings.

"I don't believe it's personnel, whoever comes in should be able to do the job," Robinson said of his side's porous defence.

"When you come in you execute the principles and the system you want to apply.

"We haven't been able to get that done, so it's definitely our (defensive) system.

"They change angles a lot and we should've executed on that. We lost the ruck but attacked well and our combinations were good."

On the eve of selections for State of Origin II, Parramatta duo Ryan Matterson and Reagan Campbell-Gillard gave good accounts of themselves in the battle for NSW spots and Eels coach Brad Arthur confirmed Matterson would re-sign on a four-year deal..

Campbell-Gillard and the Roosters' Queensland prop Lindsay Collins were both placed on report.

Roosters winger Joseph Suallii grabbed a try double to press his claim for a NSW berth.

Suallii kickstarted one of the most chaotic opening halves of the season, evading a Maika Sivo tackle to touch down in front of 21,757 fans at Commbank Stadium in the third minute.

The Eels immediately responded with late offloads from back-rower Shaun Lane to send Clint Gutherson and Dylan Brown over for tries, with Isaiah Papali'i also touching down.

Sitili Tupouniua hit back for the Roosters but just before half-time Parramatta went up a gear and Robinson's men couldn't go with them.

A try to Sivo, who had earlier sent Joey Manu flying with a one-handed fend, started on the Eels' left, went through 10 different sets of hands to the right and finished with the big Fijian crashing over on the left-hand edge.

Reed Mahoney further hammered home the Eels advantage to give them a 26-12 lead at the break.

"We've got to have that drive and the killer instinct to play like that every week," said Arthur.

"We've got to make sure we don't go to games relying on our talent. We were close to the best version of ourselves tonight and we've got to do that every week.

"I liked our second half more than our first half. They came at us extremely hard because we showed plenty of grit."

At the start of the second half Suaalii regathered his own chip kick to give hope of a response from the Roosters, but when Egan Butcher was knocked out cold, the fizz went out of the game.

Butcher was taken off the field by a medicab in the 54th minute and neither side scored thereafter.

Australian Associated Press