Nigel Llong followed the protocols and got it horribly wrong.
When the English umpire judged there was insufficient conclusive evidence to overturn a not out decision against Australian tailender Nathan Lyon at Adelaide Oval on Saturday, it was an indictment on a system which has no room for common sense.
And although on its own it didn't cost New Zealand the chance to win the test, square the series and keep their notable run of undefeated test series intact, it held a fair chunk of responsibility.
The balance of the game shifted decisively on that moment.
Had Llong looked up from his monitor, he'd have seen Lyon walking back to the pavilion.
Having seen the replay on the big screen, where a Hot Spot mark showed up, and presumably knowing he had hit the ball, Lyon made his move.
It was akin to walking after edging a catch to the wicketkeeper. Remember those days when batsmen walked? Lyon had given himself out.
Llong could have seen that and thought "to heck with this" and simply confirmed to his colleague S. Ravi that his initial decision was indeed wrong. But Llong stuck to the rules.
How can a batsman be both out and not out to the same delivery? Here you have it.
As Australian fast bowler Josh Hazlewood observed: "All that technology there and they still couldn't quite get a decision."
The International Cricket Council would frown on umpires going rogue on a system set up to help them.
Llong has not had a good series.
In the first test at Brisbane, he gave Brendon McCullum out caught at slip off his pad just as the captain, on 80, had hinted that something remarkable might just be within his grasp as New Zealand chased down 500 in the fourth innings. New Zealand had no reviews left.
At Perth in the second test, he reprieved centurymaker Usman Khawaja when he got a big edge to a ball from spinner Mark Craig. Again, New Zealand had used up their review quota.
These things can happen in the heat of the moment in the middle, but a DRS situation is different. Here umpires have a chance collectively to right a wrong.
The MCC's world cricket committee, including several of the game's best modern players, had a two-day meeting in Adelaide just before this test began.
Part of the summation of the meeting covered the DRS and a report being awaited from the Massachusetts Institute of Technology on the accuracy of the technology.
"The committee hopes that, assuming that the systems in use are accurate, it will accelerate the universal use of the DRS - which it has long supported - in international cricket," it read. Great timing, that.
Having a system where support of an umpiring colleague in 50-50 situations is locked in doesn't help.
Llong didn't help himself with his explanation for ignoring the white spot on Lyon's bat: It "could have come from anything," Llong said while deliberating out loud. Which, if right, would suggest Hot Spot is unreliable and therefore a waste of time.
A few seasons ago, it was discovered that on a cool day, an umpire had broken wind while standing beside a batsman. It showed up on his bat as a white smudge. Seriously.
The final replay Llong sought on Saturday produced a different delivery and shot. A total botchup.
Llong has been slaughtered over his blunder. He erred badly, but he can say he simply followed the guidelines and as he wasn't totally sure he couldn't overrule Ravi.
Using that, the system is at fault for not allowing an element of wriggle room, the human element coming into the equation.
And just think, it wasn't that long ago, that the fallability of the umpires was a central plank in turning to technology to give them a hand. Part of the beauty of the game, they said.
There was no beauty about this shambles.