Is EqA better than wOBA? by Colin Wyers September 9, 2009 From a recent BPro chat: Aaron (YYZ): Doesn’t the AL ROY almost have to be Elvis Andrus? He’s the 8th most valuable SS (by WAR) in all of baseball (and the 9th best SS offensively by wOBA) Christina Kahrl: Why use wOBA when EqA’s testably more accurate? BP has tested the accuracy of EqA before; however it’s notable that wOBA was not included in the comparison. So I thought I would run a quick test to see if EqA really is more accurate. I used this as my formula for calculating Equivelent Runs and this to calculate runs as per wOBA. FanGraphs figures wOBA as far back as 1974, and if we extend that far back, looking at RMSE, we discover that in fact EqA bests wOBA by a slight amount in our typical tests, looking at team runs per season: EqR wOBA_R Correl. 0.97 0.97 RMSE 27.3 27.6 MAE 21.4 21.9 I would go ahead and call that essentially a dead heat, but it wouldn’t be unreasonable to declare victory for EqA. But of course the question was about Elvis Andrus in 2009, and from 1980 onwards the advantage shifts to wOBA. Narrowing it down to 1993-2008, the modern offensive era: EqR wOBA_R Correl. 0.97 0.97 RMSE 28.3 27.5 MAE 21.9 21.7 Looking at RMSE, wOBA is better by about a run per season. I’d consider that more significant overall, and far more relevant to Elvis Andrus.