No point pursuing DRS perfection: Ponting

What Ricky Ponting labelled an "unacceptable" mistake from third umpire Aleem Dar should not stop Australia's exasperated players and captain accepting the Decision Review System will never be perfect, the Test legend says.

Dar's controversial call not to give Mitchell Santner his marching orders on day three of the Boxing Day Test against New Zealand compounded the hosts' simmering frustration with the review process, despite their dominance of the series.

Australia began celebrating Santner's wicket when they reviewed a catch to leg gully, originally deemed not out by on-field official Marais Erasmus, and replays appeared to show Mitchell Starc's bouncer grazing the sweatband on the batsman's glove.

But Dar left captain Tim Paine and his men in disbelief when he ruled there was insufficient evidence to overturn the on-field decision.

"That was a mistake from the third umpire, simple as that," Ponting told cricket.com.au. "I don't know if he rushed it a bit or didn't get enough angles that he needed.

"You could see the sweatband on the glove moving quite considerably. I'm sure they'll find a way to justify it somehow. They'll say it was inconclusive.

"But it wasn't inconclusive to me and anyone who watched those replays would say it was very conclusive, and would say there was enough evidence to overturn the decision.

"Aleem has been one of the leading umpires in the world for a long period of time, you would have thought they would look at every possible angle. That's their job.

"The umpire's job is to ask for every last bit of assistance that he can get to make the right decision and I just don't think he took enough time to do that today.

"We talk a lot about DRS and ball tracking … but when it becomes a human error, that's when it's unacceptable. That's nothing to do with the system, that's just a bad umpiring decision."

But Ponting stressed the system will never achieve 100 per cent accuracy.

Paine expressed doubt over the DRS on Saturday following a pair of decisions that went against his side and cost him a chance at scoring a maiden Test century, telling ABC Radio that he believes ball-tracking technology "is sometimes a little bit off the mark".

The skipper shook his head as he walked off after initially being given not out following an lbw appeal against Neil Wagner, yet was then forced to exit when New Zealand reviewed successfully.

Paine's frustration increased when Black Caps batter Ross Taylor was given out on field but then spared as predictive ball-tracking technology suggested James Pattinson's delivery would have gone over the stumps.

"If we're looking for perfection with the DRS, we're never going to get it," he continued.

"It's easy for me to say now because I'm not a player, but the players need to understand that the whole idea of the DRS was to take out the really bad decision, the real howler – not to make judgments on little millimetres here or there.

"Until players accept it that way, they'll always have a chip on their shoulder or a grudge on the system."

As it stands, some reviews require the television umpire to make a judgment.

Deciding whether a catch or lbw review has hit part of the bat, like in the Santner incident, is often the most contentious and difficult to interpret with certainty.

The benefit of the doubt goes to the on-field umpire; unless there is conclusive evidence to overturn the original decision, their call stands.

But other reviews, like the two lbws that did not go Australia's way, are dependent on the technology used (and paid for) by the television broadcasters.

Cameras track the path of the ball frame-by-frame, a human analyst decides which frame saw the point of impact on a batter's body, then technology predicts where the ball would have gone had its journey not been interrupted and, crucially, if the ball would have then hit the stumps.

Sometimes, Ponting points out, that technology surprises the human eye – like when Paine felt certain he'd been struck outside the line of off stump by the Neil Wagner delivery from around the wicket that dismissed him.

"As far as the ball tracking is concerned, the players have just got to understand that what they sometimes think and feel about what we've learnt about the game over the years (might be wrong)," said Ponting.

"You heard Tim Paine talking this morning about the angle (Wagner) created, he felt he would have had to be outside the line.

"I think it was actually showing that he wasn't outside the line. You just feel as a player (sometimes), 'it must have hit me outside the line'.

"With Ross Taylor's one, Painey felt like that had to be out. If you look at it, it struck him clearly above the knee roll and everything we've always learnt and been told about umpiring is that if you get hit above the knee roll … it's going to go over the stumps." 

Domain Test Series v New Zealand

Australia squad: David Warner, Joe Burns, Marnus Labuschagne, Steve Smith, Matthew Wade, Travis Head, Tim Paine (c, wk), Pat Cummins, Mitch Starc, Nathan Lyon, James Pattinson, Michael Neser, Mitchell Swepson

New Zealand: Todd Astle, Tom Blundell, Trent Boult, Colin de Grandhomme, Matt Henry, Kyle Jamieson, Tom Latham, Henry Nicholls, Jeet Raval, Mitchell Santner, Tim Southee, Ross Taylor, BJ Watling, Neil Wagner, Kane Williamson (c)

First Test: Australia won by 296 runs in Perth

Second Test: December 26-30, MCG (Seven, Fox & Kayo)

Third Test: January 3-7, SCG (Seven, Fox & Kayo)