Steve Smith walked off shaking his head after being given out in the second innings at the SCG, though it wasn’t at all clear why.

The batsman had confirmed his return to form in spectacular style, adding an 81 to his first-innings century, but was still far from satisfied.

Is it a requirement for Australian to shake their head at the umpire over every out decision?

— Jamie Cook (@JC_1973) January 10, 2021

He was initially given not out after being struck on the pad by Ravichandran Ashwin but India captainAjinkya Rahane chose to review the decision. The third umpire cited “clear daylight” between bat and ball, with neither Snicko nor Hot Spot showing any evidence of an edge.

Though Smith got a big stride in, HawkEye showed the ball striking him in line, and projected that it would have taken out a chunk of leg stump, and so the decision was overturned.

Steve Smith has walked off the SCG in despair, shaking his head all the way after technology denied him a second straight century.

You can follow our live #AUSvIND blog here: https://t.co/fhJFcQ3DS5

— news.com.au (@newscomauHQ) January 10, 2021

As he walked back to the pavilion, he made no effort to hide his displeasure at having been dismissed within 19 runs of a second Test hundred in as many innings. Some wondered whether he felt he had been given out wrongly, suggesting he might have thought he hit it, or wondered if Smith felt his long step forward should have counted in his favour.

did he not hit that??? #AUSvIND

— kj (@kelsey_jobe) January 10, 2021

Think Smith is very unlucky, There is no way that was hitting, the bounce on this pitch is decent just cant see it hitting. Never had faith in ball tracker #AUSvIND

— Matt (@Mattcedes44) January 10, 2021

Australia captain Tim Paine has voiced his displeasure at DRS decisions multiple times in this series. He was frustrated to be given out caught behind at Adelaide despite feeling that he hadn’t hit the ball, and was criticised for asking the umpire for some “f***ing consistency” after a decision he felt was similar went in favour of India at Sydney.

Steve Smith is shaking his head in disappointment on being given leg before, but that looked out the moment the ball hit his pads. Usually, all 22 know whether out. its how it used to be pre-DRS, now there is a doubt over every decision #AUSvIND

— Sanjjeev (@Sanjjeev) January 10, 2021

“Shaking the head” is specifically cited in the ICC Code of Conduct as something which can count as “showing dissent at an umpire’s decision”. However, the same section states: “This offence is not intended to punish a batter showing his/her instinctive disappointment at his/her dismissal.”