Speaking in his post-match media conference after Collingwood's 45-point win over the Swans at Telstra Dome on Saturday night, Roos said, "You'd have to say that from a neutral point of view, this group has run out of [steam] and it's hard to go back to the well all of the time.
"There's guys there that have given everything over the last five and a half years and at the moment, other teams are lifting … but the group as we know it has been so good and it's just not capable of producing the performances that they once were."
Roos said it was imperative the club remained as strong as it could without bottoming out.
"I think it's hard in Sydney because you've got to remain competitive
"I've got to take my hat off to this group, because they have been very competitive again this year," Roos said.
"We need to be competitive and we'll probably have to sit down at the end of the year and [see how] many changes we'll make – it is a very competitive market and it's a lot different to Melbourne.
"Brisbane has done a similar job and Leigh's [Matthews] done a similar job up there – they've remained very competitive since their four grand finals.
"Eighth or ninth – that's probably where the two teams who are in those northern states [sit] and it's very hard to bottom out."
Roos said his side had tailed off in the second half of the year.
"It's unlikely that we're going to do much damage over the next couple of weeks," Roos said.
"Whilst you've got to be realistic of where you're at, [we're] looking forward to the challenge of next week and playing against Brisbane and trying to get back into some form. And then clearly we've got a final to play the following week – you've really got to focus on that at the moment."