Energy transfer : when rightly dosed it allows players to excel at the game
Imagine one would use steel balls : when these hit one another there is no deformation of the surface and as a consequence all the kinetic energy of the cue ball transfers to the object ball that gets catapulted away. Similarly, billiard balls that are too hard are considered too "jumpy" which diminishes the player 's ability to control his shot and the desired impact on the object ball in terms of speed, direction and spin. On the other hand when the balls are too soft, too much of the kinetic energy of the cue ball gets dissipated in the flexing of the surface of both the cue and object balls when they hit one another. That's what players call "dull" or dead balls as part of the energy of the shot gets lost in the flexing, and one has the impression the object balls don't react enough.
The amount of rebound / energy transfer / control is totally determined by the ball material hardness, elasticity, surface vitrification and molecular structure.
Aramith has a truly unique molecular engineered resin that through the state-of-the-art moulding and the multiple curing processes and steps has resulted in the "right" mix of hardness and elasticity that results in the right dose of rebound & energy transfer that allows the player maximum control and precision in the game. Sometimes players try other competing balls but in the end they invariably switch back to Aramith for its unique combination of characteristics allowing them to excell at the game.
Furtheron, Aramith balls have a strong reputation to hold their unique characteristics longer than any other ball during its exceptionally long lifetime.
Balance / True roll
When the density of the resin is not evenly spread throughout the ball (and its parts), it results in the weight not being evenly distributed throughout the ball. This unbalance results in the ball not having a straight run and to deviate off its intended track.