It was once the rock which personified St George Illawarra's NRL dominance but coach Wayne Bennett described the defensive effort against Sydney Roosters as "heartbreaking" in their 20-12 upset loss at WIN Stadium.

The Dragons displayed a soft underbelly not seen before during Bennett's tenure at the club, the Roosters targeting the premiers up the middle to stunning effect to bring a bright end to a week from hell.

The tries conceded to props Jason Ryles and Mose Masoe from short range would have been laughable had their implications not been so serious, the Dragons without the resolve which had been their trademark.

"It's pretty much heartbreaking that stuff," Bennett said, with the Roosters' other tries to Phil Graham and BJ Leilua equally as soft.

"Round ten or 12 we were averaging 8-10 points a game against us - now you just get near us and we're going to fall over and let you score a try."

It could have been so different had Matt Cooper managed to ground the ball instead of being held up over the line in the fourth minute, but given what followed in the ensuing 76 minutes, it's hard to argue the better side won the day.

The only time the Dragons got back into the game was when the Roosters - leading 10-0 and denied a second try to Phil Graham - lost Anthony Minichiello to the sin-bin for what was deemed a professional foul following a Darius Boyd break.

"I didn't think it was deliberate," Roosters coach Brian Smith said.

"Maybe the referee - I thought he panicked."

Front rower Trent Merrin strolled over three minutes later, and while Minichiello had just returned when Cooper latched onto a Nathan Fien bomb, it looked like the Dragons were coming as they led 12-10 at the break.

But Masoe crashed over five minutes after the restart as the Dragons dawdled when Beau Scott was placed on report for a grapple tackle on Braith Anasta, while not once but twice the home side failed to defuse a Mitchell Pearce kick as Leilua put the margin out by eight points ten minutes from time.

That signalled the end of the road as the crowd headed for the turnstiles - while Jamie Soward took a seat on the bench after his back injury had left him a virtual passenger for the entire contest to that point.

The Roosters, who had been rocked earlier in the week when Todd Carney, Nate Myles and Frank-Paul Nuuausala ignored a team drinking ban and were suspended by the club, gathered for an emotional huddle in the middle of the field after the siren.

"I'm overwhelmingly proud," Anasta said.

"It's a credit to everyone, every player, everyone at the club.

"It was tough, the first few days, but the way that the guys handled it was unbelievable.

"It was hard not being distracted by what happened early in the week."

And while Bennett identified there was a problem within his squad, the answer wasn't as forthcoming.

"I've got something at the back of my mind but it's difficult right now," Bennett said.

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