When Head ran free and Smith went inward

Around half an hour into the third day's play, Travis Head was having a chat with umpire Chris Gaffaney. The Australian opener was giving the New Zealander a lowdown of last summer's Test at the SCG, as picked up over the stump mic. He noted the pitch had more grass then and the contest had more intensity, with the Border-Gavaskar Trophy still up for grabs. Head's conversation on Tuesday came against the backdrop of more temperate energy, with the Ashes already sealed.

Head was in his 120s then, in total command of proceedings and the English challenge. He was walking his runs, walking across his stumps, walking at the bowlers—simply having a blast. So much so, he distracted himself with chit-chat. And why not? For the third time this summer, Head had put England to the sword in brutal fashion, dictating the terms and tempo of the contest, rendering Ben Stokes and his bowlers helpless in their quest to stop him.

If Head's brutality—163 off 166 balls—set Australia apart at the SCG halfway through the New Year's Test, it was Steve Smith's mastery on a slowly deteriorating pitch that helped the hosts surge into a position of complete dominance with two days left.

Unlike Head, Smith spent most of his time in the middle talking to himself, as he often does when in that zone of complete control—over the Test match and his influence on it. It was trademark Smith: eccentric, with tics and idiosyncrasies tuned up to 10. That usually signals two things in Smith's world: either the surface is challenging, or he's in cruise mode and needs his fidgety mind to keep him in check.

If Smith wasn't flashing thumbs-up at bowlers, he was yelling "in ducker" every time a delivery jagged back at him. He was also distracted dozens of times by movement behind the sight-screen. He played audacious shots, especially after passing fifty, stitching vital partnerships that have taken Australia well in front and in line to finish 4-1.

During this innings, he became the second-highest run-getter in Ashes history, with eyes on turning it into a much bigger score come Wednesday.

For England, it was a day when their wheels finally began to come off. The bowling was ordinary, the catching worse. Will Jacks dropped an absolute sitter at deep backward square leg, then put down a chance off his own bowling to reprieve Head. Zak Crawley later spilled a difficult opportunity at leg-gully off Smith—similar to catches Smith and Marnus Labuschagne had taken at vital moments earlier in the series.

This exemplified how England have been unable to seize moments, let alone create them. Unlike Australia, who on the field have both created and seized these moments, and now look set to secure a commanding final Ashes win.