Munster shocked over handling of Yeo knock

Cameron Munster has hit out at the handling of Isaah Yeo's State of Origin head knock, claiming it didn't take rocket science to know the NSW lock should have left the field.

Yeo's head appeared to make contact with Josh Papalii in the first hit-up of the series, before he fell backwards and lost his balance in retreating back to the line.

He was also assisted by Blues teammate Tariq Sims as he regathered stable footing, before resuming his place defence.

The league's independent doctor classed the symptoms as a category three, allowing Yeo to stay on after only requiring an on-field check.

Yeo insisted after the match he was not concussed, and that he had merely lost his balance on the slippery surface as he got up.

The NRL were reviewing the process on Thursday morning, but noted that Yeo had passed concussion checks on field, at halftime and after fulltime.

Regardless, NSW coaching director Greg Alexander admitted on Thursday morning he immediately thought Yeo should have been removed, and that the hit had clearly affected his game - coming off before halftime and totalling only 53 minutes.

Munster went one step further, as the Queensland five-eighth claimed it was a bad look for the game.

"It wasn't rocket science, you could see he wasn't well," Munster said.

"It makes me sick (to see it) but someone's got to put their hand up and take responsibility for it, cause it's not on.

"We've been speaking about it for years and years about the welfare of our players and our heads.

"You want to showcase that in the biggest game of the year."

Under the NRL's protocols, possible head knocks are spotted before an independent doctor in the bunker pores over replays from different angles.

Motor incoordination, such as balance disturbance and clumsiness, are considered as indicators that require a player to be checked.

Had Yeo's incident been labelled a category one, he would have been ruled out of the match immediately, while a category two requires a 15-minute off-field test.

Man-of-the-match Munster complained Yeo's incident was no different to his in Game II of 2020, after his head hit the turf in the second minute and he could not return as a category one.

"I know it's an Origin game ... but someone's got to take a stand," Munster said.

"I didn't want to go off (in 2020), I passed all my HIAs and everything. But because I stumbled and wasn't right, they pulled me."

Yeo has a history with concussions, and was insistent after the Blues' 16-10 loss that he was not suffering side-effects of a head knock following the tackle.

"I felt fine," he said.

"I remember everything, I've been knocked out and it definitely wasn't that. I just lost a bit of balance.

"(It was) just the contact, I reeled out of it and I was just trying to get my footing to get back in the line."

NSW doctors were not shown replays of Yeo staggering back on the sideline, as the broadcast stayed with the play.