wOBA Primer, With a Bonus

Here’s one I wrote for USA Today Sports Weekly, which is partnering with High Heat Stats for a column focusing on a different advanced statistic every week:

    In 2012, Ben Zobrist batted .270, but was immensely valuable to the Rays. Michael Young batted .277, but provided his Rangers with negative value. Not only is Zobrist a talented and versatile fielder, while Young is a designated hitter and a defensively challenged part-time infielder, but Zobrist was much better last year at the plate.

    One measure of Zobrist’s offensive superiority is Weighted On-Base Average, or wOBA, where Zobrist outpaced Young, .365 to .297.

    Created by Tom Tango, wOBA uses linear weights to determine the value of a player’s offensive contributions. Where on-base percentage treats all hits equally and slugging percentage ignores walks and exaggerates the benefit of an extra base hit relative to a single, wOBA combines the aspects of offense measured by OBP and slugging, as well as the net effect of stolen bases and times caught stealing, into one all-encompassing measure of offensive production.

    The weight of each outcome in wOBA reflects the likelihood of the outcome leading to a run, independent of actual base-out scenarios. In 2012, per FanGraphs, a home run was worth 2.33 times as much as a single, which in turn was worth 1.28 times as much as an unintentional walk.

    Young had 11 more hits than Zobrist in 17 fewer plate appearances. Zobrist, though, topped Young in doubles (37 to 27), triples (7 to 3) and home runs (20 to 8). Zobrist also walked 64 more times, creating far more runs while using fewer outs. While Zorilla finished in the top 15 among qualified hitters in the American League in wOBA, Young was in the bottom 15.

    League-average wOBA hovers around .320. Though nobody knew it at the time, Babe Ruth was the sultan of wOBA, owning the three highest single season figures, peaking at .598 in 1920. Barry Bonds leads post-WWII players with a .544 wOBA in 2002.

And as a bonus for loyal Replacement Level Readers, here’s my first draft, which used different players to illustrate the same point.

    In 2012, Prince Fielder of the Tigers batted .313 with 30 home runs and 108 RBI. Kansas City’s Billy Butler batted .313 with 29 home runs and 107 RBI. Both are lumbering sluggers who add little value on the field or on the bases, and on the surface, they looked very similar last year.

    If we want to know which player provided more value at the plate, Weighted On-Base Average, or wOBA, is a great place to start.

    Created by Tom Tango, wOBA uses linear weights to determine the value of a player’s offensive contributions. Where on-base percentage treats all hits equally and slugging percentage ignores walks and exaggerates the benefit of an extra base hit relative to a single, wOBA combines the aspects of offense measured by OBP and slugging, as well as the net effect of stolen bases and times caught stealing, into one all-encompassing measure of offensive production.

    The weight of each outcome in wOBA reflects the likelihood of the outcome leading to a run, independent of actual base-out scenarios. In 2012, per FanGraphs, a home run was worth 2.33 times as much as a single, which in turn was worth 1.28 times as much as an unintentional walk.

    Fielder and Butler had nearly identical totals of doubles, triples, and home runs. The only differences between them were 31 more walks and 10 more hit-by-pitches for Prince and 12 extra singles for Country Breakfast, in 11 fewer plate appearances. A single is more valuable than a walk, as a single often allows a runner to take an extra base. But with all those walks and hit-by-pitches, Fielder used 20 fewer outs than Butler. This shows up in Fielder’s .398 wOBA, third in the American League behind Miguel Cabrera’s .417 and Mike Trout’s .409, enough to make Prince a reasonable MVP candidate most years. Butler’s .377 wOBA placed ninth.

    League-average wOBA hovers around .320. Babe Ruth owns the three highest single season wOBA figures, peaking at .598 in 1920. Barry Bonds leads post-WWII players with a .544 wOBA in 2002.

While the Zobrist-Young piece was more fit for a broader audience, since it’s obvious that Zobrist was a better player than Young, it’s really a comparison of wOBA to batting average, which most of us know is a deeply flawed statistic. What I preferred about the Fielder-Butler angle is how remarkably similar those two guys look in all the triple crown stats, and how wOBA calls out differences that one must dig a little deeper to find.

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One Response to wOBA Primer, With a Bonus

  1. Pingback: What skills do the best players have in common? | bring on the stats

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