If you follow baseball you’re bound to run into some advanced statistics, eventually. There are a plethora available, some good, some not so good. One of the best of the good ones is wOBA, developed by Tom Tango.  This article is here to help you understand how wOBA works, and what it means.

wOBA stands for weighted On Base Average, and as such, is set to the scale of On Base Percentage (OBP) where roughly .335 is average, .400 is excellent, and below .300 is terrible. wOBA is created by using linear weights – a way of measuring every plate appearance a player has and determining the overall offensive value of those plays. Every play has a specific run value, which Tom Tango beautifully lays out in The Book: Playing the Percentages in Baseball. In short, wOBA puts proper weight on the events that happen on a baseball field.

The way the run values were determined was by going back through years of play by play data and recording the average run values for each event. Tango then came up with the formula for wOBA, which is: wOBA= (.72 x NIBB + .75 x HBP + .90 x 1B + .92 x RBOE + 1.24 x 2B + 1.56 x 3B + 1.95 x HR)/PA. NIBB is Non Intentional Base on Balls and RBOE is Reach Base On Error. This number can now be used to compare the number of runs a player contributed to his team above average, or wRAA (weighted Runs Above Average). All you do is take wOBA – league average wOBA / 1.15 x PA.

If any of you are further interested in wOBA, be sure to check out fangraphs.com and insidethebook.com.