Tuesday April 25, 2006 3:10 am
Just Another Metric Monday: On Base Percentage (OBP)
A few years ago, Michael Lewis’ Moneyball became one of the most talked about books about baseball and seemed to divide the way people in baseball looked at players into two factions. On one side, you had the old school scouts who looked at physical attributes, broken down into the golden five tools - hit for average, hit for power, running speed, arm strength, and fielding ability.
On the other side, you have the statheads AKA sabermetricians. I must say that I put myself in this group, although I personally do not assess players strictly on numbers. I like to look at things such as movement on a pitcher’s fastball, the angle or a batter’s swing, and other physical tools outside of the basic five tools listed above.
That all said, I’d like to spread the word of sabermetrics and provide the readers of Endscore a glossary of terms and concepts used by us statheads when looking at the numbers. Each Monday, I’ll provide a definition to a sabermetric term or two and hopefully allay any fear of all those acronyms and formulas to the casual baseball fan.
For the first edition of It’s Just Another Metric Monday, I’ll take a look at the concept made popular by Lewis’ Moneyball - On Base Percentage (OBP). On Base Percentage is basically the percentage of time a batter gets… well… on base. Batting Average (BA) gives you the percentage of time a batter reaches base safely by getting a hit. On Base Percentage adds into the formula the number walks or bases on balls (BB) and hit by pitch(es)(HBP) in addition to the normal BA formula.
So, here’s the OBP formula: Hits+BB+HBP/At Bats+BB+HBP+SF (Sacrafice Fly).
Why is this stat so important? Well, it’s a better indicator to the potential of a batter getting on base and scoring a run, which we all know, is the ultimate stat in determining who wins a game – score more than the other team and you win! So, ideally, teams will want to get as many people to reach base safely.
Here’s a strict hypothetical. Ichiro Suzuki and Adam Dunn both step up to the plate 650 times. Ichiro gets 200 hits and 50 walks while Dunn gets 170 hits and 120 walks. Neither gets hit by a pitch and for the sake of this argument, neither have a sacrifice fly eitehr. Since most people readily recognize batting average, let’s look at them – Ichiro is hitting .308, while Dunn is hitting .257. Obviously, Ichiro’s average looks a lot better. But, now let’s check their OBP. Ichiro has a .357 OBP and therefore a 35.7% chance of reaching base safely and potentially scoring a run. Dunn has a .376 OBP and therefore a 37.6% chance of reaching base safely and potentially scoring a run. That’s a significant increase in percentage for Dunn when you add in the walks.
So, if someone asks you if you’d rather have the .308 BA hitter or the .257 BA hitter, remember the answer isn’t always so cut and dry.
Next week, I’ll tackle the new stat darling – OPS, which is On Base Percentage (defined above) Plus Slugging Percentage (which I’ll define next time as well to give you an overall understanding). Catch you all next week… I am now taking off my SABR hat.
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