“This week, baseball resumes its prodigious production of numbers in another season of 2,430 games with 21,870 innings and approximately 700,000 pitches during 166,000 at-bats. The rage to quantifyâ€”to reduce reality to measurable unitsâ€”is an impulse in modern societies. In baseball, it produces illuminating metrics. For example:
The objective is to win, which means scoring runs while efficiently getting the other team to make 27 outs. Every three outs, you must start over. Until recently, most people assumed that the key to runs was hits. Hence a misplaced emphasis on batting averages. But counting all hits alike is as foolish as counting different denominations of currency as identical. Nowadays, more emphasis is placed on not making outs. Hence the importance of on-base percentage, which is (hits + walks + hits by pitch)/(at bats + walks + hits by pitch + sacrifice flies). That led to the statistic OPS, which is on-base percentage + slugging percentage (which is total bases/at-bats).
But Bill James, a pioneer of novel metrics (see “The Mind of Bill James” by Scott Gray), says OPS takes the elements of run creation and puts them together incorrectly. “They shouldn’t be added together, they should be multiplied. A team with a .400 on-base percentage and a .400 slugging percentage would score more runs than a team with .350 and .450, although both add up to .800 OPS.” James suggests calculating “runs created”: (hits + walks – caught stealing) x (total bases + .7 steals) / (at bats + walks – caught stealing).”