Isaah Yeo at centre of concussion controversy in Panthers' historic NRL triumph

Questions are being asked as to whether the NRL relaxed its concussion stance for the finals after Panthers co-captain Isaah Yeo passed his Head Injury Assessment in Sunday night's grand final. Yeo was left motionless on the ground after copping Koby Hetherington's shoulder to his head while trying to make a tackle in the 57th minute.

Yeo, whose head also slammed into the ground, was prone for a couple of seconds as players rushed in to show their concern, with the referee stopping the game. The Panthers co-captain managed to get to his knees as he chatted with a trainer, before it was decided he would go off to undergo an HIA.

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Andrew Johns said in commentary that Yeo was "in all sorts", while 'NRL Physio' Brien Seeney wrote on social media: "Isaah Yeo off for a HIA after heavy contact to the head and lying motionless on the ground. Hope he’s OK - has an extensive history with concussion issues."

Yeo headed to the sheds to have the HIA, but many were left shocked when it was reported that he'd passed the test. The back-rower came straight back onto the field after the required 15 minutes off, and was on hand to help the Panthers snatch an incredible 26-24 victory.

But questions are being asked about how Yeo was allowed to return to the field given how serious the incident appeared at first. The 28-year-old appeared fine as he delivered his post-match victory speech, but as we know that's not always a good indicator.

"I remember the tackle. I remember hitting Hetherington, I got his shoulder on my head," Yeo told AAP on Monday. "I wasn't knocked out, I was just stunned. I came to, I passed the test, I was fine. I just felt helpless (not knowing the score)".

Yeo was involved in similar controversy in State of Origin last year, when he copped a heavy hit to the head in the opening seconds of Game I. The NSW back-rower looked very groggy and was stumbling around, but the NRL's independent doctor - making a first appearance in an Origin series - assessed Yeo and deemed him fit to stay out on the field.

Questions raised over NRL concussion stance

While the NRL has implemented a number of strict protocols in recent years and is taking head injuries and concussions very seriously, a number of instances in the finals have raised eyebrows. Kalyn Ponga, who also has a history of concussions, wasn't forced to undergo an HIA in the dying stages of Newcastle's win over Cronulla in the first week of the finals.

The Knights fullback was hit in the head by a high tackle, before his head also went into the ground violently. However he was allowed to stay on the field and convert the winning penalty goal, and never underwent an HIA. A failed concussion test would have meant Ponga couldn't play the ensuing semi-final against the Warriors, which the Knights lost anyway.

Nathan Murphy ruled himself out of AFL grand final

It came in complete contrast to what occurred in the AFL grand final on Saturday when Collingwood defender Nathan Murphy ruled himself out despite passing an HIA. Murphy revealed he passed the concussion test because he's memorised it, but knew he wasn't right to keep playing.

“I passed the test, but I ruled myself out," he told The Age. "I had a bit of blurry vision, and with my concussions, I kind of get them delayed. I know the concussion test off by heart now ... I’ve done that a couple of times now, where I’ve passed it, then we’ve ruled me out.

“I’m totally fine now, actually pretty good. I can’t remember too much of the game, but I’m remembering a lot of this [post-match celebration], so that’s all that matters.”

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