Stats All, Folks: What in the world is wOBA? -
Paul Folkemer

Stats All, Folks: What in the world is wOBA?


Welcome back to Stats All, Folks, where we’re continuing our season-long tour through sabermetric statistics and what they mean. Previous editions covered WAR and BABIP/FIP.

Next on the agenda: wOBA.

What is wOBA?


Designed by sabermetrician Tom Tango, wOBA (weighted On-Base Average) is a sort of all-encompassing offensive stat that blends elements of on-base percentage and slugging percentage. It measures not only how often a hitter gets on base, but the ways in which he does so.

After all — as any baseball fan knows — a home run is more valuable than a triple; in turn, a triple is more valuable than a double, which is more valuable than a single, which is more valuable than a walk. Traditional OBP doesn’t make a distinction between the different methods of getting on base. Slugging percentage does make that distinction, but doesn’t include walks or hit by pitches.

The most common way of combining those two stats, of course, is OPS (on-base plus slugging), which simply adds the two numbers together. But wOBA is considered a more precise way to weigh the value of each type of outcome.

The formula varies slightly each year, but it’s usually something along the lines of the following (per FanGraphs):

Unintentional walks times 0.69, plus hit by pitches times 0.72, plus singles times 0.89, plus doubles times 1.27, plus triples times 1.62, plus home runs times 2.10, all divided by at-bats plus unintentional walks plus sacrifice flies plus hit by pitches.

Got all that? There will be a quiz later.

Even if you’re not going to commit that formula to memory, you can see the basic premise: walks and hit by pitches are given the lowest value, working up to home runs as the highest value. So, a batter who hits two doubles and a homer in 10 plate appearances would have a higher wOBA than a batter who has two singles and a walk in 10 plate appearances, even though their OBPs would be equal.

Consider another example. A hitter who draws five walks in 10 plate appearances is more valuable than a hitter who has one single in 10 plate appearances. That’s something that slugging percentage wouldn’t properly demonstrate, but wOBA would. It’s a better reflection of how productive a hitter has been.

Frequently asked questions

Q: Doesn’t wOBA basically measure the same thing as OPS?

A: Sort of, and the two stats usually correlate pretty well. When ranking the 2016 Orioles hitters by wOBA, they’re in almost exactly the same order as if you rank them by OPS. However, OPS has a major flaw. It assumes that OBP and slugging percentage are equally valuable, when in fact getting on base is more important for scoring runs than slugging is. wOBA does a better job of emphasizing the importance of OBP.

Q: Can I pronounce it “Woe-bah?”

A: Sure. Go nuts.

Q: What is considered a good or bad wOBA for a hitter?

A: A league-average wOBA is usually in the range of .310-.320. Like any stat, it varies from year to year. Last season, the MLB-average wOBA was .318. According to FanGraphs, the most elite hitters usually have a wOBA around .400, while anything .300 or below is considered poor.

In 2016, the best wOBA in the majors among qualifying hitters belonged to the now-retired David Ortiz (.419), just ahead of AL MVP Mike Trout (.418). The Orioles’ top performer was Manny Machado (.366).

The worst wOBA was the woeful .256 posted by Marlins shortstop Adeiny Hechavarria in 547 plate appearances. No Orioles’ regular was particularly terrible in the wOBA department last year; J.J. Hardy and Matt Wieters had the lowest at .307 each. (Reserve catcher Caleb Joseph posted a .188 wOBA in his tragically poor 2016, but, to be fair, he only had 141 plate appearances.)

The best wOBA seasons in Orioles history

Achieving an exceptional wOBA is no easy task. It requires a hitter to be excellent at both getting on base and hitting for power. It’s not enough to be a one-dimensional slugger — witness Mark Trumbo, who led the majors with 47 home runs last year, only to end up with a good-but-not-great .358 wOBA. Trumbo’s mediocre ability to draw walks and get on base dampened his overall offensive value.

By the same token, you usually can’t get to a .400 wOBA just by walking and slapping singles all year. You need to have real extra-base power, too, since wOBA accounts for the types of hits you get.

The Orioles have had a few outstanding wOBA performances amidst their 63 full seasons. You might assume that the franchise’s best single-season wOBA would belong to Frank Robinson in 1966, when he won the Triple Crown and the AL MVP award.

That’s an excellent guess, valued reader. Robinson did have an incredible .447 wOBA in 1966, tops in the majors that year. But that’s only the second-highest mark in Orioles history.

The best wOBA season actually belongs to Jim Gentile in 1961, when he erupted for 46 home runs and 141 RBIs, batting .302 and drawing 98 walks. It resulted in a gargantuan .453 wOBA.

Amazingly, Gentile’s was only the third-highest wOBA in the majors that year, behind Norm Cash (.488) and Mickey Mantle (.478). Yet none of them won the MVP, an honor that instead went to Roger Maris for setting the single-season home run record. (In case you’re wondering, Maris’ wOBA that year was .424, tied for sixth in the majors.)

The worst wOBA in Orioles history

Among players with 400 or more plate appearances, that dubious honor falls to an otherwise great Oriole, Paul Blair, who struggled to a .238 mark in 1976.

Although Blair was a pretty good hitter for much of his career, nothing went right for him at the plate in that campaign. He drew only 22 walks in 413 plate appearances, batted .197 and hit just three homers. It was his final season as an Oriole.

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