I mentioned the other week with Tuaupiki that the concussions can be all over the place. Nikorima got ruled out the week before after looking fine and making a few follow up tackles. Tuaupiki in his collision in looked like Rapana took the impact more in the head. Tuaupiki went off and failed and Rapana was left on the field.
Capewell ended up finishing the game from what I remember. Was the knock not picked up? I suspect he reported some symptoms post match.
There was a big shot in the Bulldogs game and the player came back on. His looked worse than all of the examples above.
Goes to show how each individual is different.