The Umpire Decision Review System (DRS) has proven to be a pivotal player in the 2013 Ashes Series. Jonathan Trott has been given a formal apology from the International Cricket Council (ICC), the contentious dismissal of Usman Khawaja was dubbed by Kevin Rudd as “one of the worst umpiring decisions I have ever seen,” and Kevin Pietersen was left fuming as he stormed back to pavilion adamantly not out. The tactical elements of Australia’s unsuccessful usage of the DRS have also come under intense scrutiny, more so than even fielding settings or batting order.

The DRS was devised in 2009 for teams to review and overturn wrong decisions made by the on-field umpires and, excepting India’s refusal to allow its use in any test matches in which they take part, the use of referrals, like in tennis and the NFL, was implemented relatively smoothly into the cricketing arena. However, what’s gone so terribly wrong with this particular Ashes series? The answer is Hot Spot.

Hot Spot, derived from military innovations, is an infra-red imaging technology that, as the name might suggest, captures heat signals. Most importantly, Hot Spot cameras create a greyscale replay where the ball will illuminate a white spot on anything with which it comes in contact. For cricket purposes, Hot Spot was immediately useful in confirming whether or not a batsman had in fact edged the ball to the keeper or the slip cordon, or whether a delivery struck the batsman’s pad or bat first in determining LBW decisions.

Problems have now arisen, however, with the knowledge that Hot Spot is not 100% accurate. In particular, faint edges are occasionally missed by the technology and do not illuminate a perceptible white spot on the bat as expected. Its inventor, Warren Brennan, also suggested that the application of Vaseline or lubricant to the edges of a bat would reduce the chance of nicks being perceived by Hot Spot, due to the decreased friction between bat and ball. A scandal broke last week when Channel Nine reported that batsmen, most notably Kevin Pietersen, had been applying silicon tape to the outside edge of his bat for this same purpose. Although the ICC and players have since denied the allegations, it still raises the question whether Hot Spot can be entirely trusted.

In most cases this slight imprecision is not important; if, during a review for caught, Hot Spot captures a white spot on the bat, the decision is literally black and white – irrespective of the on-field umpire’s original decision, the batsman is out. But what these revelations of Hot Spot’s inaccuracy have dramatically changed is the third umpire’s decision-making process when assessing reviews where the ball does not conveniently leave a visible white spot on the bat.

Under the rulebook governing of the DRS, the third umpire needs substantial evidence to overturn an on-field umpire’s decision. Imagine a batsman is given out for an appeal of caught behind – even if the batting side has a referral up their sleeve and the batsman made no contact with the ball whatsoever, the odds are severely against a correct decision being made. Why? Because when Hot Spot shows no white spot on the bat, how does the third umpire know that the edge wasn’t just too faint to show up? There is too much doubt and Hot Spot is no longer sufficient evidence to definitely say that the bat never touched the ball.

To make up for Hot Spot’s inaccuracies in these situations, Marais Erasmus, the third umpire officiating the 2013 Ashes Series, has been forced to assess other pieces of information to confirm whether Hot Spot was correct and there was in fact no contact between bat and ball. Most notably Marasmus has had to resort to the adjudication of sound, attempting to detect the distinctive but by no means unique sound of a ball nicking the edge of a bat. This wanders into dangerous territory because such a sound might excite the fielding side and the crowd into a raucous appeal, but it could just as easily have been produced by the bat skimming the pitch or clipping the batsman’s pad during the stroke.

Interestingly the Snickometer, introduced in televised coverage of the cricket, was deemed too inaccurate to be used by third umpires during the DRS. The Snickometer synchronises the video of a slow motion replay with a graph of the waveforms of any sound produced during each frame – a short sharp peak in waveform evident in the frame where the ball is passing the bat is seen as proof of leather hitting willow.

Instead the third umpires are required to watch endless slow motion replays and try and pinpoint the origin of the sound themselves, while also trying to perceive any daylight between bat and ball or any deviation of the ball’s course once it passed the batsman. The modern technology of Hot Spot is seen as too inaccurate so Marasmus has had to use technologies that have existed since the 1950s. Although slow motion replays have since been far refined, they are surely far more inaccurate than the Hot Spot they have now in many circumstances replaced.

Ultimately the problem boils down to the fact that the third umpire’s mistrust of modern technology, in this case Hot Spot, has meant that decisions are now vastly more dependent on individual interpretation, and where there is interpretation there is undoubtedly human error. The DRS was not implemented to overturn human error on the field with human error off the field.

The answer? Cricket should trust technology, and cricket should trust Hot Spot. If there’s a spot on the bat, the bat hit the ball. If there’s no spot on the bat, the bat didn’t hit the ball. Black and white, clear as crystal – even if it’s only 99% accurate, there will be far fewer howlers than have already been made in this Ashes series.