Yeo's health became one of the chief talking points out of NSW's series-opening 16-10 loss at Accor Stadium in Sydney when his head appeared to make contact with a rampaging Josh Papalii on the first hit-up of the game.
The Penrith middle fell backwards, then lost his balance as he got up and retreated to the line before being assisted by Blues teammate Tariq Sims.
The incident was reviewed by the NRL's independent doctor in the bunker, who only deemed it worthy of a category three before Yeo passed an on-field concussion check.
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.
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," Yeo said.
"I remember everything, I've been knocked out and it definitely wasn't that. I just lost a bit of balance.
"When you're knocked out, you don't remember anything. I remember absolutely everything.
"I remember the play (leading with) the wrong shoulder, all of that sort of thing. It was all good."
Yeo admitted he spent the minutes following the hit believing he may be pulled off the field for a full HIA, given the independent doctor may have seen him lose his balance.
Motor incoordination, such as balance disturbance and clumsiness, are considered possible symptoms of a head injury as per the NRL guidelines.
But the 27-year-old said in this instance, the balance loss was not related to any head injury.
"(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," Yeo said.Â
"It's all fine. I thought (trainer) Travis (Touma) would come and check, just because I was trying to get my balance. But my head feels fine, no stress."
Yeo played 53 minutes compared to his usual 80, coming off the field before halftime.
His absence clearly impacted the likes of Nathan Cleary and Jarome Luai, who use Yeo as a link man in attack at Penrith.
NSW advisor Greg Alexander admitted on Thursday morning he immediately thought Yeo should have been brought off after stumbling, and that the Panthers star was impacted by the contact for the rest of the game.
"I automatically said that was a category-one, we have to get him off," Alexander said on SEN.
"Isaah, despite staying on the field, was obviously affected. And probably shouldn't have stayed on as long as he did."
