While sitting and watching a player's game how should one study his weak-points? I win 3 out of 10 games with my opponent. I obviously would like to win more. How should I study his weaknesses while observing him play? Is there some kind of chart professional coaches maintain when they study opponent's weaknesses?
well, check if he can do every kind of shot. which ones are weaker? does he have a good backhand? footwork? defense? once u find these out you can play the weaker aspects to win.
The thing is, if you find a weakness in an opponent and keep targeting that weakness, they will wise up and work on that weakness. Being a good observer and knowing their weakness is one thing, minimising your own weaknesses is another. In what way is he beating you all the time? Is he unpredictable? is it his fitness? or skill? There are so many factors that could be involved. And sorting out or just knowing your own weaknesses would be just one method you could use. Finally, try and keep ahead of them and use the element of surprise in your game.