Early in the second half there was another incident and the players started pestering Barnes to go to the TMO for further judgment.
Barnes asked whether they were questioning his ability. In that instant, there was further confirmation about the danger for rugby if they widen the use of replays. The more it is used, the more players will use it for their perceived advantage.
It's easy to imagine those ugly pileups which blight football matches when players harangue match officials, often jostling them or their opponents.
There was a rugby convention the referee would converse only with the captains of both teams during a match. Some of that strictness has eased but, in this World Cup, it seems to be taking on another life.
The cause of that can only be the excessive referrals to the TMO, which started in the opening game at Twickenham when Jaco Peyper and his deputies blinked at every roar from the crowd.
Rugby is an imperfect sport with a bloated book of rules. Widening the scope of the TMO for decisions other than foul play outside a scoring movement will open up the system to extended abuse. It's also a handy vehicle for sides feeling the fitness pinch to implore the referee to check the big screen for some make-believe indiscretion.
World Rugby officials have been trawling through all the footage and citing players for actions they felt were unlawful. Some have been upheld, like the eye-gouging from Pumas lock Mariano Galarza, although it was odd they did not cite England flanker Tom Wood for his kick which connected with the Welsh fullback's head.
Picking through those details afterwards is an appropriate way to judge any foul play which has not been clear to the match officials.
Those individuals should take note of Barnes' work - as long as he continues to take charge as he did at Villa Park.
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