Sixties are the new hundreds with new balls and pitches

Steve Smith says scores of 60 for top-order batters are now sometimes as valuable as centuries after a "perfect storm" of changes to balls and pitches.

Smith posted his first Test hundred in 25 innings on Sunday, ending the longest drought of his career after a stretch dating back to June 2023.

His 101 helped Travis Head dramatically shift the third Test, as Australia finished day two at 7-405, in a match under significant threat of being ruined by rain.

The ton was also the first by an Australian batting in the top four this summer, and only the 13th of any top-order player in 18 Tests in the country since the start of 2021-22.

Players largely put that down to a change in Kookaburra balls at that time, with an extra layer of lacquer applied and a plastic lining under the seam making the seam more prominent.

"The wickets got greener as well," Smith said.

"It's kind of like a perfect storm coming together.

"The first 35 overs of the innings is very challenging at the moment, with the significant seam movement.

"The last three years has been probably been the hardest that I've experienced in my career in terms of the amount of movement that's been generated."

Averages of top-four batsmen have dropped in Australia, New Zealand, South Africa and Bangladesh since the ball change.

Of nations who use a Kookaburra, only on the flatter wickets of Pakistan and Sri Lanka have such impacts not been felt.

And it is in Australia where the effect has been most significant, with top-four batters averaging 31.21 since December 2021, compared to 41.61 in the decade before that.

"The scores have come down. Bowling averages have come down. Batting averages have come down," Smith said.

"Five years ago, you saw 400 or 500 being scored consistently in the first innings. If you put a three in front of it these days, you're usually in a pretty good position.

"So you've got to think about that as well when you're thinking about play.

"Sometimes if you don't get a hundred, it's not the end of the world. A good 60 or a good 30 at times can be really crucial and match-winning for a team."

The other side of that, though, was on show in Australia's innings on Sunday, with the extra lacquer Kookaburra staying harder for longer than in the past.

That has formed part of Australia's thinking this summer, with an aim to bat time early and have the counter-attacking Travis Head and Mitch Marsh coming in after 40 or 50 overs.

"If you get through that period, you've got guys like Travis and Marshy and Alex (Carey) coming in," Smith said.

"The ball still bounces off the bat a lot harder than it used to.

"Previously you get to those positions when the ball gets a bit softer, you'd see catches in front of the wicket and it would be a bit more difficult to score."