I'll start with an admission, I can't explain wOBA (weighted on-base average) to you in full detail.
Rather, I'll tell you what it tries to capture.
Let's start with the premise that slugging percentage sucks. It's a good idea and all, but it loses steam pretty fast. Is a triple really worth three times as much as a single? Not necessarily. Is a walk really neutral? Not at all.
The antidote is on-base percentage, which assigns equal value to all outcomes so long as the batter reaches base. We've now swung too far on the statistical pendulum. I mean, a home run is worth more than a single. Maybe not four times as much, but certainly more.
Enter the savior, wOBA.
Weighted on-base average takes every outcome of an at-bat and assigns it a value based on how many runs, on average, that outcome produces.
Sounds good, but how the heck do you solve that riddle?
Well, people smarter and more dedicated than I thumb through the annals of baseball history and make note of what has already transpired.
What happened after every walk? Every single? Every fielding error?
For example, we know a home run is worth more than one run on average because there can be players on base when the home run occurs. So we look through past game results to see how many home runs have been hit with zero, one, two and three men on base.
Using that data, and some fancy math, we calculate a home run's average value in a neutral context and turn it into a co-efficient. Basically we want a figure that expresses a home run's worth if we had no idea how many players were on base.
We can do the same thing with singles, walks, errors, etc.
Now take those new values and multiply them by the number of times a given batter produced each outcome. Add them all up, divide by the number of plate appearances and you, my friend, have yourself a wOBA.
Whew. I hope I explained that right.
(Check this link, this link and this link for better explanations.)
If you're still dubious, check the list of last year's best hitters according to wOBA: Jose Bautista, Miguel Cabrera, Ryan Braun, Matt Kemp, Prince Fielder, Adrian Gonzalez.
Sound like a list of the best hitters in baseball to you?
Since fantasy baseball's highest aspiration is to reward good performance, wOBA seems a good place to start.
Who Would Benefit: Jose Bautista, David Ortiz, Lance Berkman
Who Would Suffer: Alex Rios, Alex Gonzalez, Gordon Beckham