Does an instructor have to be able to tool every person that exists to be knowledgeable or a good teacher? Do you think Helio Gracie, in his final days, would be able to beat "athletic athletes" (as opposed to unathletic athletes??)? Probably not. Would you have things to learn from him? Probably so.
Jiu jitsu culture is stuck on the "great man theory" and it kills me. You don't have to be a top level competitor to have a deep knowledge of BJJ. Likewise being a top level competitor doesn't mean you can teach worth a damn (or even consciously know what you're doing that makes it work). Cus Damato raised Tyson, Patterson, and Torres, and taught some of the greatest coaches that have ever been...yet his boxing career never left the amateur level (due to eye injury, but whatever). Should he be ignored because he couldn't tool any person that walked in the door?
I look forward to the day when BJJ culture lauds good competitors, and good instructors, and understands the two categories don't have to (or may ever) over lap.