- Physical maintenance: Diet, fitness, hydration, sleep, etc. These things matter. Even for someone who's young and seemingly indestructible, these things affect performance. A manager or coach can help guide a player with these things, but a player ought to be able to regulate things himself.
- Racket assembly: Conceivably, a player could go through his entire career without assembling a racket, if his parents do it during his developing years and then a coach does it in the heart of his career. But what if something comes up and you need to do it yourself half an hour before match time - will you be unable to do it? Or maybe you'll be able to do it, but the resulting racket will perform differently from what you normally use. Different ways of gluing rackets will result in varying performance.
- Ball selection: I've seen world top ten players who accept the opportunity to select a match ball, and then process a few dozen balls doing things that I think have very little chance of isolating the superior ball.
- Sportsmanship: Table tennis players are relatively good with this, but there are exceptions. A player who lacks sportsmanship will have a harder time joining a team, working with coaches, and securing endorsements. Personally, I will root against a poor sport every time.
- Know the rules: A basic understanding of the rules is not enough. This would be like a CPA having only a basic understanding of the tax code yet expecting to be successful. A serious player should have a serious understanding of the rules, including the yearly rule changes which generally take effect every September. And including the rules of the draw; no, the player seeded #2 is not guaranteed to face the player seeded #3 in the semis.
- Appeals: This is a subset of rules knowledge, but I'm emphasizing it because players don't seem to understand it. Unless you're playing in a team contest, the coach or captain cannot make an appeal to the referee; only the player can. This is an explicit rule. Therefore every player needs to know what can be appealed, and how to communicate with officials.
- Speak English: I've been watching the US Open of tennis and, like in table tennis, a tennis player will occasionally need to speak with the umpire to get clarification about a ruling. Unlike in table tennis, all of the tennis players seem to know enough English to do so. They don't walk to the umpire's chair and start gesticulating with their hands or speaking in their native tongue (unless the umpire also speaks it).
Most of us saw the weird stuff that happened during the women's singles final of the 2012 Olympics. Ding Ning was penalized for one thing, then another, and didn't seem to completely understand what was going on. Would there have been those problems if the Chinese players knew English?
The Chinese players are the best in the world. They are so good that I believe they can afford to spend a little less time in the gym, and a little more time in the classroom. The result may not necessarily be more world titles, but rather, more world success. Can you imagine what it would look like if, after winning the gold medal match at the Olympics or Worlds, the winner could give an interview in English with no translator?
In my opinion, it would look like a big step forward.