Add in that New Zealand had made a calamitous blunder in failing to refer a denied lbw appeal against Smith on 14 from Trent Boult and it all added up to an awful night in the field.
Smith was struck on his pads by Boult and replays showed it would have hit near the top of off stump.
Excuses could be made that, with only one unsuccessful DRS referral available, New Zealand might have wanted to be careful. The point was Smith was the most important wicket and it had to have been worth the punt.
How Smith made them pay. He had been dropped down the leg side one run earlier by wicketkeeper BJ Watling off Boult and on 152 Colin Munro spilled him at square leg, diving right.
Throw in Head's letoff, on seven, Matt Henry dropping a regulation catch at deep mid off above his head and it was a sloppy performance.
An idea of how well Australia depressed the accelerator can be seen in the fact the first 100 runs took 138 balls; the surge from 200 to 300 just 53.
Yet it had begun promisingly. Boult, the pick of the bowlers until pasted in his last couple of overs, did sterling work and Lockie Ferguson and Colin de Grandhomme drew false shots.
All eyes were on New Zealand's new speed hope Ferguson and he had a rough night, finishing with one for 73 off nine overs. Yet there were signs that New Zealand could be onto something good.
His speed was impressive - the first five balls in his second over were all clocked in excess of 150kmph, but he tired and got tonked, and should have come out of the attack sooner than he did.
There were few signs of smart thinking among the bowlers, precious few yorkers and as well as Smith did, New Zealand were guilty of forgetting their lines.
Boult's two for 51 off 10 overs were the best return, while Matt Henry and Jimmy Neesham got two apiece but cost far too many runs.
''It's a nice feeling," Smith said after his innings.
''I had a bit of luck but you try and make the most of it. It was a pretty good wicket, the new ball nipped around a little bit, then things got a little bit easier from there."