I have seen many strong players after taking up coaching have their own strength rapidly fall. It's almost universal with some rare exceptions.

That is why I am impressed by WGM Nafisa Muminova who is not only coaching (her students are playing here too) but is married, has a baby on top of that! All these would be a deterring factors to a chess professional. Despite the odds she seems to playing at peak strength in the current Penang Open consistently playing on top 10 board.