OBP

On-Base Percentage (OBP) measures the most important thing a batter can do at the plate: not make an out. Since a team only gets 27 outs per game, making outs at a high rate isn’t a good thing — that is, if a team wants to win. Players with high on-base percentages avoid making outs and reach base at a high rate, prolonging games and giving their team more opportunities to score.

The formula for OBP is simple:

OBP has become synonymous with the book “Moneyball” because at in the early 2000s, teams weren’t properly valuing players with high OBPs and the Oakland A’s could swipe talented players for cheap. These days, every team has come to accept how vitally important OBP is to their success, and that particular “market inefficiency” has been closed.

Context:

Please note that the following chart is meant as an estimate, and that league-average OBP varies on a year-by-year basis. To see the league-average OBP for every year from 1901 to the present, check the FanGraphs leaderboards.

Rules of Thumb

Rating OBP
Excellent 0.400
Great 0.370
Above Average 0.340
Average 0.320
Below Average 0.310
Poor 0.300
Awful 0.290

Things to Remember:

● OBP is considered more accurate than Batting Average in measuring a player’s offensive value, since it takes into account hits and walks. A player could bat over .300, but if they don’t walk at all, they’re not helping their team as much as a .270 hitter with a .380 OBP.

● A player’s OBP is a good predictor of their future OBP after 500 plate appearances. So if Pujols has a .500 OBP after only 50 plate appearances, don’t expect him to continue reaching base at that rate.

Links for Further Reading:

On-Base Percentage – Wikipedia

On-Base Percentage – TangoTiger