possible to be a good coach but losing player?

not thinking of anyone specifically, there seems to be alot of people who are breakeven/losing players that seem to understand many dynamics of the game. I play golf at a fairly high level and its widely known that to teach the game you dont have to be able to play it. Is there anyway this could apply to poker? i.e someone could coach a player to become a better player than himself, a winning player, yet that player would still come to this person for advice? Or be able to teach someone to beat a limit that you yourself couldn't beat?

I think Gakn29 coaches gavz101 which is about as close to this as I could think of.
http://australian-casinos.org/

P.s Im talking about someone who would be a losing player overall, not meaning someone losing over a certain sample size etc etc