DRS labelled a 'failure' after Marsh dismissal

The Decision Review System's ball-tracking technology has come under fire again following Mitchell Marsh's dismissal on the fifth morning of the first Commonwealth Bank Test at the WACA Ground.

Marsh was trapped leg before wicket for 26 after South Africa successfully reviewed a not out decision on the field, handing star quick Kagiso Rabada his fourth wicket.

Despite the ball seemingly angling down the leg side, the ball-tracking technology showed it to be hitting more than 50 per cent of Marsh's leg stump and he was sent on his way.

Former Australia captains Michael Clarke and Mark Taylor both questioned the accuracy of the technology's ball path, while Marsh's batting partner Usman Khawaja also questioned the on-field umpires.

And former Test quick and Marsh's former international and state teammate Mitchell Johnson slammed the decision on social media, labelling the DRS a "failure".

"I was certain that was missing the stumps," Clarke said on Wide World of Sports.

"When you look at that replay, I thought it was definitely swinging too far and missing the leg stump. He'll be really disappointed with that.

"It has clipped his toe, then clipped his pad, and then got onto the bat.

"But what I don't agree with is the line of the delivery once the ball hits him on the toe ... I believe the line of that delivery is going down and missing leg stump."

Image Id: 736841A5D0F94D5BBC31475B928F4730 Image Caption: The ball-tracking technology shows the ball to be hitting the stumps // Channel 9

Clarke's co-commentator Taylor agreed, saying the ball-tracking technology appeared to show the ball to be seaming back away from Marsh, which was enough to hit at least 50 per cent of the leg stump and overturn the on-field decision.

"Watching those replays I thought Mitchell Marsh would be fine," Taylor said.

"He was given not out so the technology has to prove that he was definitely out to overturn the decision.

"It almost looks like the ball seamed back a little bit and just done enough for 50 per cent to hit the outside of the stump, meaning the not out call was overturned.

"I reckon the ball is going to flick the stumps at best. But to be overturned, Mitchell Marsh is very unlucky."

It's the second time in the match the DRS has come under fire, following Steve Smith's dismissal on the second day of the match.

Umpire Aleem Dar judged Smith to be out LBW after he was struck on the pads advancing down the pitch to debutant spinner Keshav Maharaj during the first session on Friday.

Smith immediately signalled for a review but despite being several paces down the pitch, the tracking showed the ball to be clipping leg stump, which was enough for Dar's original decision to stick and send an unhappy Smith on his way for a four-ball duck.

Quick Single: Smith dismissal sets 'bad precedent'

The decision came under heavy criticism from Test greats Shane Warne and Kevin Pietersen in the Channel Nine commentary box.

"To me this is a bad decision," Warne said. "The DRS system is there to get the right decision.

"There is an argument that (this delivery) is hitting the stumps and it should be out. But for me, I'd make it this simple: the on-field decision should be taken out of the equation.

"It should be very simple. We know (ball tracking) isn't 100 per cent accurate.

"Let's say if more than 40 per cent of the ball is hitting the stumps, you're out. If it's less than 40 per cent, you're not out. Irrelevant of what the on-field decision was.

"I can't believe that's out. It sets a bad precedent for me for the rest of the game that a batsman can run out of their crease on a low pitch and be given out."