BBCOR (Batted Ball Coefficient of Restitution), the baseball bat standard that replaced BESR (Ball Exit Speed Ratio)
Many are still confused with the BBCOR standard and exactly what it means. Here’s a very simple explanation.
Rather than measuring the ratio of the ball exit speed to pitch and bat speeds (like BESR), BBCOR measures the trampoline effect of the bat. With the BESR standard, when a pitched ball made contact with an alloy or composite bat, the barrel would flex inward somewhat and the ball would retain a portion of its energy. This resulted in hits that were longer and harder. Wood bats don’t have that give to them and the ball loses much of its energy upon impact. The BBCOR standard ensures that non-wood bats perform more comparably to wood bats in an attempt to level the playing field.
It also accounts for how bats perform after they’ve broken in. Since the dawn of composite bats, it was found that the more they were used the better they performed. This led to tampering with the bats to artificially accelerate the break-in process and improve bat performance (rolling anyone?). With BBCOR, bats are now tested after various stages of simulated use in the lab, so that a bat never performs beyond the BBCOR standard at any point during its useful life.