After looking at what is the basis for much of our sabermetric offensive value in wOBA, I wanted to take a look at the next stat which attempts to build off of Bill James stat RC (runs created) and combine it with wOBA. Runs Created was originally instituted by James to display how many runs a player was responsible for instead of trying to value R, RBI, SB, etc, which can often be misleading. Not every run scored is fully the value of the base runner and not every RBI is earned by the hitter.
Tom Tango took this and instead of using the raw numbers, used wOBA, which is a more accurate valuation of a player and used this to calculate wRC. The equation for wRC is:
(((wOBA – lgwOBA) / wOBAScale) + (lgR/PA)) * PA
According to FanGraphs the wOBAScale is usually around 1.15, but changes year to year and is calculated based on wOBA weighting.
This stat is very informative, but much like OPS and wOBA it can be difficult to gauge what the number always means when comparing to other players. To account for this Tango created wRC+, which much like OPS+ scales to 100 to gauge value compared to league average. To calculate wRC+ is a bit more involved, but according to this you calculate like this:
a = league runs per PA
b = wRAA/PA
c = a/b + 1
d = 100*c
d = wRC+
*wRAA is another Tango stat and is similar to wRC, but tells you the number of runs created above average and not total.
Once you calculate wRC+ you can use it much like OPS+ and it scales much the same way. Here are some values for 2011 to display what each stat looks like.
Player wRC wRC+ Jose Bautista 139 181 Jacoby Ellsbury 132 150 Jason Bay 57 100 Carl Crawford 55 83 Alex Rios 41 59
This should give you an idea of how the stat works, but to be more specific Ellsbury was worth 77 more runs to the Red Sox than Carl Crawford or 32 more runs than the average player. Looking at wRC+ Ellsbury was 50 percent better than league average. As you can see a wRC of about 57 was average in 2011.