SYDNEY Swans midfielder Ryan O'Keefe says a lack of confidence is one of the reasons behind his side's disappointing loss to Fremantle on Saturday.

The 37-point loss to the resurgent visitors followed heavy losses to Geelong and the Western Bulldogs and O'Keefe said the slump was taking its toll on the players' collective psyche.

"Footy's a confidence game, and maybe a bit of the confidence has been zapped a bit," he said.

"There's no excuse for it, it's our own doing. We can't worry about what the opposition are doing or who the opposition are; it's up to us. We can only control what we're doing out there and we're not up to scratch."

That mindset was reflected in the Swans' third-quarter revival, when they dominated general play but still lost the term, three goals to two.

"When you've got a bit of a run, you'd like to get as much scoreboard pressure as possible," O’Keefe said.

"Sometimes you keep going and you can't put the score on the board and then you get a quick reply, and all that hard work has been a bit useless."

With injuries and form issues creating potential openings in the side, O'Keefe said it was imperative that the incoming players seized their chances.

"At the moment, our depth is really getting tested and anyone who gets the opportunity really needs to step up," he said.

"Anyone who comes in new as a first-gamer, or with a handful of games, or 200-plus games, they've got to make sure when they come in the side that they're doing their part."

One of those new players to shine was livewire half-forward Gary Rohan, who showed the SCG something of the lightning pace and equally adept football brain that made him such a highly prized pick in the 2009 NAB AFL Draft.

"He's going to be an exciting player. He had a crack today and showed that he competed well," O'Keefe said.

"He's got plenty of zip and with these young guys and the experience they're getting, I think you learn more from losing so hopefully in the last three weeks, they're learning a lot."