YOUNG Sydney star Isaac Heeney quickly noticed a worrying lack of voice among his teammates when he returned to the senior side.

It reflects the unlikely crisis that has engulfed the Swans, who are a game clear at the bottom of the ladder in a season in which they were tipped widely to be premiership contenders again.

Heeney was Sydney's best in their upset 19-point loss to Carlton on Saturday in his second game back after recovering from glandular fever.

"The first game I came back, it (was) really weird - compared to last year, it's dead quiet," Heeney told the Game Day program.

"We had a good start last week and then, just dead quiet.

"It's surprising and a bit of a weird vibe at the moment, but we just need that confidence back, play our normal brand of footy."

Teammate Dan Hannebery said voice and effort were basic areas where the Swans were now lacking.

"They're two things that don't require any talent - pressure and voice," Hannebery said.

"(They've) been a trademark of our game and two things you can control and do quite easily, no matter if you've played one game or 200.

"They're two areas I think we can fix really quickly.

"As a leadership group, we have to drive (that)."

Coach John Longmire was fuming after the Carlton loss and said the Swans were playing an unacceptable brand of football.

"I basically echo Horse's words - we're not working hard enough as a group at the moment, both with the ball and without it," Hannebery said.

"We're certainly getting beaten around that scrambled, contested situation.

"The numbers might have been even, but certainly a lot more of their (forward) thrusts were a lot more effective than ours.

"It's an area of the game that we pride ourselves on and we have to keep working hard."