The NRL confirmed on Monday that Klein would only act as a stand-by official for the semi-final round, as they admitted Melbourne had three incorrect calls go against them in the 12-10 loss.

On a busy day in refereeing ranks, the NRL's head of football Graham Annesley also urged social media trolls to lay off touch judge Michael Wise.

Wise was also dropped with Annesley following an error late in the match, and has since come under heavy fire on social media.

But it is the omission of Klein that is most notable, given he refereed last year's grand final and the last two Origin series.

Klein's biggest error came in his failure to penalise and sin-bin Canberra's Elliott Whitehead for taking Ryan Papenhuyzen out off the ball as he supported a Melbourne break.

Assistant referee Chris Sutton had yelled out for the penalty to be blown, but Klein has since told officials he didn't hear that over the crowd noise.

Klein then penalised Jarrod Croker on the next play for holding down, but failed to sin-bin him for the professional foul given the Storm's momentum from the break.

"In either of those cases the offending player should have been sin-binned," Annesley said.

"The referee (Klein) didn't hear the (original Whitehead) call because there is a lot of noise in the stadium listening through a small earpiece.

"But holding down excessively under the posts in a try-scoring situation, in our view, should see a player sin-binned."

Annesley also said Klein was wrong to not penalise Whitehead earlier in the match for a strip, when Sutton had again told him to call the indiscretion.

The football boss did however defend the 21 penalties blown in the match, which was more than double any other game from the weekend.

Meanwhile Wise was dropped for incorrectly ruling Storm winger Suliasi Vunivalu had touched the sideline as he caught a short kick off in the game's penultimate minute.

But Annesley said the touch judge was struggling with both the decision he'd made as well as abuse and threats he'd copped online following the tight finish.

"Some of the stuff that has been floating around on social media, including vilification of him as a person and threats, are completely unwarranted," Annesley said.

"No one is out there trying to make errors. These people have families and they commit to the task.

"Yes he made a bad decision but it doesn't make him a bad person or a bad official.

"People who make threats and verbal character assassinations of people online really need to pull their heads in."

Annesley also stressed that Vunivalu had come close to the touchline and not "nowhere near it" as he said some had claimed.

Australian Associated Press