Does one need to be a top player to be a top coach? The question often comes up, and there's an easy answer. No.
However . . . and this is a big HOWEVER . . . it's difficult to become a top coach without being a top player first. It's a matter of opportunity. If you are a member of a National Team, you train for many years with other top players and top coaches, and if you are really paying attention and become a student of the game, you gain the experience necessary to be a top coach.
It's possible to be a very good basics coach, one who can train new and intermediate players very well, without being as experienced working with top players. But the key problem to watch for here is that many coaches who teach basics teach them in a way that will later hurt the player. For example, some hold back on teaching the loop in rallies, especially the backhand loop, for so long that hitting becomes ingrained, and so looping never becomes ingrained or comfortable. Or they have the player use beginner's sponge so long that their development is held back because they develop a game around beginner's sponge instead of a modern game based on modern sponges. So even coaches of beginning and intermediate players need to have enough experience with top players to see how they develop so they can teach players a foundation that leads to becoming a top player.
Some believe you can be a self-taught coach, and there's some truth to this. But there will always be major holes in your coaching if you don't have the opportunity to spend lots and lots of time with top players and coaches when they train. Even tactical coaching is limited if you haven't spent a lot of time with the player you are coaching when he's practicing. You might be a good tactical coach from personal experience and from watching top players on video and analyzing what you see, but you have to see what the player is doing in practice to see what he can really do. You might see him have trouble with a shot and not know if he normally has trouble with that shot or if he's just off or nervous. You might see a weakness in an opponent that seems to play into your player's strengths, but if the player hasn't practiced that type of sequence, he might not be comfortable doing it. So being around top players and coaches when they train is important if you truly want to be a top coach. This doesn't mean you can't be a decent coach; but to be a top coach you need the full experience.
Suppose you were not a top player, but somehow spent years watching top players train and work with top coaches, and really paid attention? Then you could also become a top coach. However, it's difficult to find such opportunities unless you are a top player. If you aren't a top player and want to be a top coach, you have to find opportunities to be around top players and coaches when they train, even if it means volunteering to help in some way, or just observing, perhaps for years, as you learn what top players learn in the many years they train to become a top player. This means showing up to watch their training sessions or attending training camps, where you observe, analyze, and ask questions.
There’s also the problem that you can’t really train one-on-one with a top player if you aren’t also a top player, but you can still hit with non-top players, feed multiball, run group sessions, and perhaps block for top players in some drills. (One key thing for non-top players who want to be top coaches – become an expert in feeding multiball. How do you do this? First, watch top coaches do it – both their technique and the drills they do. And second, by practicing, not just with players, but on your own, by yourself, with a box of balls. And then volunteer to do it in group sessions.) There are numerous examples of non-top players, or players who were good but never national team level, who became top coaches.
You want to be a top coach? Start attending training sessions and camps, but not as a player, but as an observer or assistant coach (possibly as an unpaid volunteer), and that’s where you learn. If your level is high enough, most coaches would gladly welcome an assistant coach who can be a practice partner (if an odd number of players) or feed multiball – and while doing this, you learn from that coach and from the top players in the session. Do this long enough, and become a student of the game, and you’ll start really seeing the sport differently – and you’ll be on your way to becoming a top coach.