Player's characteristics represent his skills and are the most important factor in determining his performance on the court.
They are split into 6 categories on the Player's profile screen: Offense, Move, Serve, Rally, Resistance, Mental.
Characteristics are rated from 1 to 99, with 1 being very poor and 99 being outstanding.
In order to properly assess a player's ability from his characteristics, it is important to understand how each characteristic reflects the player’s performance. As such, explanations of all the characteristics visible on the player's profile are provided below:

Power: How strongly your player hits the ball

Laser vision: Reflects your player's ability to estimate where the ball will bounce in his side of the court

Control: How accurately your player can reach a determined zone with the ball.

Agility: Reflects how well your player coordinates all of his moves

Balance: Your player's ability to suddenly change his direction in spite of the speed, or to hit the ball while in motion

Acceleration: Your player's max. speed, and how quickly he can reach it

Analysis: Your player's ability to anticipate his opponent's moves and shots

Reflexes: How fast your player executes his shots, once he is on the ball

Serve: Reflects your player's ability to serve strongly and precisely

Sidespin: Reflects your player's ability to slice his services

Volley: How often your player will make volleys and how effective they will be

Underspin: How well your player makes an underspin

Backhand: How good is your player's backhand

Forehand: How good is your player's forehand

Return: Reflects your player's ability to master his returns of serve

Topspin: How well your player makes a topspin

Stamina: Slows down the reduction in the physical shape bar

Vitality: Increases the max. points in the physical shape bar

Consistency : Determines your player’s capacity to hold an exchange

Listening: How well your player understands what you ask him, and how fast he does so

Confidence: Increases the max. points in the mental shape bar

Motivation: Increases the replenishment of the mental shape bar during a match

Self-control: Slows down the reduction in the mental shape bar

Turning points: Reduces pressure maluses during break, set or match points. It can even convert them into bonuses.