Over the past couple weeks, you undoubtedly have seen me make mention of the stat WAR. Some of you, maybe most of you, know what WAR is, but for those of you who don’t I thought I’d give a quick explanation. A quick Google search would probably allow you to find an explanation, but I’ll try to put mine in terms for beginners to understand.
To start, WAR stands simply for Wins Above Replacement. WAR takes a players “counting” stats, i.e. home runs, and translates them into “rate” stats. Rate stats are things like average and OBP that can either increase or decrease. WAR translates counting stats not into average, but uses more complex stats such as wOBA. What wOBA basically is is a rate stat that is linearly weighted to favor a high OBP over a high slugging percentage. Since a point of OBP is worth more than a point of slugging percentage, this makes sense. For reference, .333 is close to league average, under .300 is below replacement, from .333 to about .370 is above average, .370 to .400 is very good, and above .400 is an allstar. This year the Twins wOBA’s range from Joe Mauer, who has an otherworldly .435, to our second base trio, who have wOBAs of .268 (Punto), .241 (Tolbert) and .233 (Casilla) respectively.
WAR doesn’t directly use wOBA, but instead wOBA is converted to wRAA. The calculation is much simpler than it seems. To do so, just take player x’s wOBA minus the league average wOBA. Then divide the resulting number by 1.15 and take that number times the number of plate appearances. This number is then adjusted to his home park’s environment (so that a player’s value isn’t dramatically impacted by playing in Arlington vs. playing in San Diego), and there you have the first part of WAR.
Defensively, WAR relies on a formula called UZR, which stands for Ultimate Zone Rating. Here is a quick explanation of all the components of UZR. To calculate a player’s defensive value, you add up all the UZR accumulated at all positions.
However, all positions are not created equal. For example, a +10 first baseman is worth much less than a +10 shortstop. To quantify this, Tom Tango, one of the world’s smartest humans, came up with a positional adjustment scale, which is as follows:
Catcher: +12.5 runs
This number is then added to the player’s hitting value to come up with a RAR, or runs above replacement, value. To convert this value to wins is very simple. 1 win = 10 runs.
Could you do this calculation yourself? Sure. Would you want to? Not when Fangraphs has it all easy to access and free.