DRS ruling stuns Siddle in Hobart

The rules governing cricket's ball-tracking technology has left players, pundits and fans shaking their heads after a baffling ruling on day three of the first Test.

With the West Indies hurtling towards an innings defeat, Peter Siddle got a delivery to jag back towards opener Kraigg Brathwaite, striking him on the pad.

Australia's vocal appeal was turned down by standing umpire Marais Erasmus, prompting captain Steve Smith to send the decision upstairs.

Replays showed no edge and the Virtual-Eye ball-tracking technology showed the ball to be crashing into leg stump.

But the system returned a ruling of 'Umpire's Call', despite showing a significant part of the ball to be cannoning into the wicket.

The decision stunned the Australian players, and raised more than a few eyebrows in the stands.

Spin legend Shane Warne labelled the decision "ridiculous" on Channel Nine's commentary while former Australia and Netherlands quick Dirk Nannes was equally as confused.

"It just has to be out," Nannes said on ABC Grandstand.

"I trust the technology on this one; I think that's exactly where the ball was going.

"It's the rules that govern the interpretation of whether it's out or not that are incorrect in this one. It was going to smash leg stump.

"I thought the initial decision was incorrect. Live I thought 'that's out'.

"If you look at the image, you look at the frame of where that ball was going to hit, you can't help but shake your head.

"The ball hit the batsman in front of middle and off. It's not missing leg stump. And it's hit him on the knee. It's not going over."

The ICC's Playing Conditions for Test matches indicate that the ruling of 'Umpire's Call' in this instance would have come down to a matter of millimetres.

Law 3.3, which outlines the process of consultation for Player Reviews, states: "If a ‘not out’ decision is being reviewed, in order to report that the ball is hitting the stumps, the evidence provided by technology should show that the centre of the ball would have hit the stumps within an area demarcated by a line drawn below the lower edge of the bails and down the middle of the outer stumps."

Spinner Nathan Lyon was also left shaking his head at a ruling by Virtual-Eye on day two, when Kemar Roach earned a reprieve.

WATCH: Roach earns a reprieve on day two

Erasmus was again the standing umpire who turned down Australia's initial appeal and the ball-tracking technology showed the ball to be just clipping the top portion of leg stump.

Unlike the Brathwaite incident – where the consternation arose from the rules that govern the technology – Lyon's frustration was caused by the path that Virtual-Eye determined the ball would have taken had Roach's pad not intervened.

"I was definitely surprised," Lyon said. "When it first hit 'Roachy' I thought it may have been sliding down leg, if anything. But when I asked Marais and he said it was height, I thought 'it's not going over, I don't think'.

"But there you go – DRS."

He then added: "Enough about DRS."