Core Torque
This is an assigned value that indicates how violent a ball will break. A high torque ball will tend to skid/flip, and a low torque ball will tend to arc smoothly.
Radius of Gyration (RG)
This is an indicator of how quickly a ball will hook. A low RG ball will tend to hook sooner and smoother than a high RG ball will.
Track Flare (RG)
This is an indicator of how much of the ball surface will contact the lane. It affects how quickly the ball will hook and how much it will hook when it reaches the dry part of the lane. A high flaring ball will hook sooner and more than a low flaring one.
Coverstock (RG)
This refers to the material of the bowling ball shell. An aggressive coverstock will have a higher coefficient of friction than a mild one and thus will bite the lane more strongly given the same grit polish and the same lane condition. The core torque, RG, track flare, and ball layout will also have an impact. The surface of the ball (including the type of coverstock, nature of coverstock, and the grit), will have the greatest impact on how the ball will behave. Some experts say the surface is 75% of the total reaction. In todays "high tech" world this simple fact is often overlooked.