It depends entirely on the sport.Not all good practitioners are great teachers
A fast paced sport like basketball is difficult to coach when a player doesn't know how he creates a result.
It happens unconciously without concious thinking.
Not so for a slower paced game like golf where thinking time is in plenty.
90% of the shot is in the setup, it's possible for an experienced eye to tell how the shot will go before it is played. The techniques of the game are passed on only by word of mouth.
A player is running to catch a ball travelling at 60mph. He has to be in exactly the right place at the right time.
Thousands of calculations are going on in his head which he has no knowledge of.......how fast the ball is moving, how fast he has to run, a projection of where the ball will be 2 seconds from now and at what distance from the ground, and all those calculations are being updated every 100 milliseconds to be fed into his muscles to increase/decrease speed.....jump/nojump, raise hands at the right time at the right angle to catch the ball.
Impossible to compute conciously.
Skill acquisition passes thru 4 levels
L1- you don't know that you don't know
L2- you know that you don't know
L3- you don't know that you know
L4- you know that you know
There are many players who reach L3 and never go beyond it for the rest of their lives.
Only 5% of L3 players make it to L4.
The L3 players can become greats, but the L4s are the legends, the biggest difference is that the L3s have off days, whereas the L4s can produce their best at will.