Yes, it is.
My ex was a professional hooker for a long time but she weren't no expert on human biology. She even gave a crap blow job.
What a stupid comparison. Can you explain why is it comparable with Sampras being expert on tennis because he was a top professional player for a long time?
Point is, you can be good at doing something without being good at talking about it. You can "know" how to do something as in being able to do it, without being able to explain how you do it, or knowing anything about anybody else who can do it.
Not necessarily. Maradona was the best football player ever and he was a disaster as a coach and anything he says about the sport is bullshit 90% of the time.
If you are not
good at talking
about tennis it does not
mean that you are not