COR (Coefficient of Restitution) and Compression are two of the most important performance measurements in a baseball. Together, they help determine how "live" the ball feels, how fast it comes off the bat, and how firm or soft it plays.
They are not a layer of the ball. The construction of every layer, from the core to the cover, is what determines them.
COR measures the ball's rebound efficiency, or how much energy is returned after impact. A higher COR generally means:
COR is heavily influenced by:
COR is typically tested by firing a baseball at a controlled speed against a hard surface and measuring how fast it rebounds.
Compression measures the firmness or hardness of the baseball when pressure is applied.
Higher compression baseballs:
Lower compression baseballs:
Compression is affected by:
Compression is tested by applying force to the baseball and measuring how much the ball compresses under pressure.
COR and Compression work together to influence:
Small changes in the core, windings, stitching, and materials can significantly impact both measurements and the overall consistency of the baseball.
