The Swans suffered successive heavy losses to Melbourne and Geelong before embarking on a four-game winning streak that included wins over finals rivals Hawthorn, Fremantle and the Western Bulldogs.
Roos said the turnaround had come as a welcome surprise.
“There’s a clear difference in our form now than a month ago. Did any of us see it coming? If I was brutally honest, no,” he said before training at ANZ Stadium on Friday afternoon.
“I thought we were okay against Geelong… we got beaten by 51 but we did actually play pretty good footy. That was a reasonable result, but certainly after the Melbourne game you couldn’t have predicted that we’d have a month of football like we’ve had.”
Roos dismissed suggestions that the Swans would suffer from hosting a final at ANZ Stadium instead of their traditional SCG home.
The Swans have played four finals at ANZ since it opened, winning three, while playing just one at the SCG - the memorable semi-final against Geelong in 2005.
“I heard someone call it a neutral venue. I’ve never been on a plane and travelled interstate to a neutral venue in my life,” Roos said.
“Before we played North (in 2008), people said we should be playing at the SCG. Before we played Freo (in 2003), people said we should be playing at the SCG. It will be an ongoing debate about this venue but we’re happy to play out here.
“Carlton would give themselves a chance playing here; they’d give themselves a chance playing at the SCG, otherwise why would you even bother fronting up?”
Of the Swans’ inclusions, Roos said Tadhg Kennelly was a definite starter, while Dan Hannebery was “95 per cent certain” of returning after a tight hamstring.
Ruckman Shane Mumford (knee) was in the most doubt but he was running freely in the warm-up and Roos said he remained a “70-30” prospect.
“Indications are [Mumford] should be fine, but there’s a difference between running and playing footy,” he said.
“We’ll test him out a little bit today - he won’t do too much work - and we’ll hope that he’s fine by Sunday.”
