The Moneyball Metric
For a hundred years, baseball scouts obsessed over Batting Average. Then, in the early 2000s, the Oakland Athletics (famously chronicled in the book Moneyball) realized a massive market inefficiency: teams were severely undervaluing players who drew walks.
The On-Base Percentage (OBP) metric proves a fundamental truth of baseball: You cannot score runs if you do not get on base, and getting on base via a walk is just as effective as getting on base via a single.
Expanding the Definition of Success
Unlike Batting Average, which only counts base hits, OBP measures how often a player avoids making an out, regardless of how they achieve it.
The Formula
The numerator includes every possible way a player can safely reach base under their own power. The denominator includes every single official plate appearance.
OBP = (Hits + Walks + HBP) / (At Bats + Walks + HBP + SF)
Evaluating OBP
Because OBP includes walks, it is always higher than a player's Batting Average.
- An OBP of .320 is considered league average.
- An OBP of .360+ is excellent, typical of an All-Star leadoff hitter.
- An OBP of .400+ is elite MVP territory. Barry Bonds holds the all-time single-season record with a reality-breaking .609 OBP in 2004, meaning he safely reached base over 60% of the time he stepped to the plate.