Monday, May 3, 2010

Royals wOBA, wOBA, wOBA

Just to satisfy my own curiosity, I made the below chart to compare current Royals' career weighted on-base average (wOBA) through May 2nd. The third column is the player's age. We're obviously dealing with vastly different sample sizes for some guys, and guys who are at different parts of their career arc. Jason Kendall is nowhere near a .336 anymore: his last three seasons have been .272, .293 and .290.

You might notice from the chart that the Royals are old and terrible at baseball.

If you're not familiar with wOBA--I consider it the ultimate measure of a hitter. Here's my brief, somewhat simplified understanding of it: First, batting average and slugging are both flawed, for one because they completely exclude walks. Pure on base percentage (or average) is much more useful than AVG or SLG, but is still flawed because different events, such as a walk or home run, are valued the same. OPS (OBP+SLG) is maybe a little better yet, but still retains the flaws of OBP and SLG and probably overvalues SLG in relation to OBP.

WOBA solves all of these problems by adding "weights" to the different outcomes of a plate appearance based on how many runs the average walk, single, double, triple, and home run create. Tom Tango, wOBA mastermind, came up with these values for the different outcomes:

HR 1.70, 3B 1.37, 2B 1.08, 1B 0.77, non-intentional BB 0.62

Then to come up with a number that would be familiar, wOBA is scaled to look like OBP numbers that baseball nerds are familiar with. In Tango's words, "an average hitter is around 0.340 or so, a great hitter is 0.400 or higher, and a poor hitter would be under 0.300." You really don't have to fully understand all the specifics behind the number; just know that it is awesome. You can find wOBA stats at FanGraphs.


  1. It's interesting to see the roster with the wOBA stat (which I am not too familiar with).

    The surprises to me are Mike Aviles, thought he would be higher, and Alex Gordon, thought he would be lower.

    I, for one, love all the "new" sabermetricsesque baseball stats, but I always wonder how more casual fans view all the stats.

    Sometimes I think a baseball math nerd can just create a stat to fit the point he wants to make... Like wording a survey to get the results you want.

  2. Thanks for the comment Travis. Aviles really hurt his numbers by playing injured last year. His wOBA was .360 in '08. Early returns this season show he could be back at that level. I sure hope so.

    The advanced stats are much kinder to Alex than traditional ones, which is why lots of stat-heads feel he didn't deserve the demotion. He has an idea of the strike zone, something the Royals clearly do not value.

    Numbers can certainly be presented in ways to fit a point, but I don't think wOBA is misleading at all. I think Tom Tango's attempt was to grade hitters as accurately as possible, and I think he nailed it.