So, this is info.
I know a guy who is a coach. He is a pretty good coach for any level up to about 2200 USATT level He could coach people higher than that. But I know a lot of good coaches who would probably be better for players higher level than that. But this guy is amazing at working with people who are adult learners who seem like they just have no talent for the sport/game.
Now, there are two people I know, who this guy coached who started at a level that was really quite low. One was a woman. One was a man. The woman was in her late 50s or early 60s when he started working with her. The man was mid 60s. The woman had trouble even making contact with the ball a lot of the time. To me, the amount they both got better working with this one particular coach was pretty staggering.
I am confident that if it was any of the other coaches I know, who are all great coaches, these two would not have gotten as good as they did with the coach the ended up working with. This guy just has a way of working with adult learners that seems to be quiet effective.
How good did they get? Well, I would say, going from not being able to put the racket on the ball on a consistent basis to 1200-1300 is pretty darn good improvement. And that is what looked like happened from where I stood. But I did not have a tournament rating to look at. She may have played tournaments. But I don't think so.
The guy showed pretty remarkable improvement as well. Not sure of a real rating for him either. But he got to what I feel is a pretty respectable level. But of them started quite late. Both of them started without table tennis or other racket sport experience.
But, with a coach that was working with them the way he would with younger players, they would not have made anywhere near as much progress. The coach worked with them in a way that was very effective for getting adult learners to make real improvements. Yes, the determination and dedication that these two had, the time these two invested in improving was a big determining factor as well. But without the way this coach worked with them, I am pretty confident they would not have made the kind of improvements they did.