A) How tough are you to beat? On a scale from 1-10, honestly answer where you stack up. Players who are tough to beat are no fun to compete against. These players never give up, make life miserable, rarely miss, are mentally tough, don't take unnecessary risks, do not beat themselves, are lovers of the game, and more often then not, they are in excellent physical condition.
Now lets flip the scale around...
B) What is your Upset Quotient? On a scale from 1-10, honestly answer your ability to upset players better than you. These types of players come in all shapes and sizes, they don't fit one particular gamestyle. Immediately what comes to mind are big hitters of the ball who are loose mental canons. This fits the stereotype of someone who would be able to upset a highly ranked player, but some of the best players in the world are counterpunchers ala Murray, Nadal, Jankovic, Simon, Chang, Hewitt, the list goes on and on.
At the end of the day, you only have control over one scale and that is HOW TOUGH ARE YOU TO BEAT? If you improve this scale, you have greatly increased your chances of becoming a better tennis player.