On-Base Percentage (OBP)
Description:
If you’re a hitter, what’s the most important thing you can do when you go to the plate? Quite simply, not make an out! Since there’s no time limit in baseball, outs are gold and making lots of them frequently is never a good thing – that is, if you want to win. And how do we measure how good players are at not making outs? Hello, On-Base Percentage (OBP). The formula is very simple:
These days, OBP is synonymous with the book “Moneyball”, mostly because at that time teams weren’t properly valuing players with high OBPs and the Oakland A’s could swipe talented players for cheap. These days, all teams (with the apparent exception of the Royals) have come to accept how vitally important OBP is to their team’s success.
Context:
2009 OBP Numbers
| OBP | |
| Joe Mauer | 0.444 |
| Alex Rodriguez | 0.402 |
| Jason Bay | 0.384 |
| Carl Crawford | 0.364 |
| David DeJesus | 0.347 |
| David Eckstein | 0.323 |
| Jeff Francoeur | 0.309 |
| Yuniesky Betancourt | 0.274 |
Things to Remember:
- Don’t ever use batting average again. OBP is much more important because it takes into account hits and walks. A player could bat over .300, but if they don’t walk at all, they’re making too many outs and not helping their team as much as a .270 hitter with a .380 OBP.
- As for sample sizes, a player’s OBP is a good predictor of their future OBP only after 500 plate appearances. So if Pujols has a .500 OBP after 50 plate appearances, don’t expect it to keep up.
- If you’re using OBP to evaluate a player, it’s a good idea to use other statistics too, like their rate stats.
Links for Further Reading:
