Heavy full contact sparring is the only sparring that matters.
What it takes punch a person hard in the head is very different to what it takes to strike a person with light/medium contact.
What it takes to stand in front of a person who is trying to really hit you hard is very different, physically and emotionally, to what it takes to stand in front of a guy who isn’t really trying to hurt you.
Spar hard with a guy who is only used to light sparring shows quite quickly that the skills are only partially transferable.
If people are getting concussed (and I totally agree that any form of concussion requires immediate stoppage and a long time out) then generally the pairing is wrong.
LOL.. really, what else did you hear?.. did you hear that he was voted Man of the Year by Kung-Fu Magizine?