05 — Performance Measurements

COR & Compression

COR (Coefficient of Restitution) and Compression are the two most important performance measurements for any baseball. Together they determine how "live" the ball feels, how fast it comes off the bat, and how firm or soft it plays.

COR and compression testing — measuring rebound efficiency and firmness to ensure consistent ball performance across a production batch.

What is COR?

COR measures rebound efficiency — how much energy is returned after impact. Tested by firing the ball at a controlled speed against a hard surface and measuring the rebound speed.

  • Higher COR = more exit velocity, more liveliness, greater distance potential
  • Influenced by core design, rubber composition, winding tension, and construction quality
  • Consistent COR across a batch = predictable, reliable performance ball to ball

What is Compression?

Compression measures firmness — how much the ball deforms when pressure is applied. Tested by applying a controlled force and measuring the degree of deformation.

  • Higher compression = feels firmer, holds shape better, used at higher levels of play
  • Lower compression = softer feel, reduces impact force, common in youth and entry-level balls
  • Affected by core materials, winding tightness, yarn composition, and construction density



Why They Matter Together

COR and Compression work in combination. Together they influence:

  • Exit velocity — how fast the ball leaves the bat
  • Feel off the bat — the sensation of contact for hitters
  • Durability — how well the ball holds its performance over time
  • Pitch response — how the ball behaves when thrown and caught
  • Overall game performance and consistency

Small changes in core materials, windings, stitching, and leather can significantly impact both measurements — which is why manufacturing consistency matters as much as material quality.