Using data from 2012, let’s look at a couple of leader boards. The list below displays the top 10 batters who drove in runs at the highest rates:
Batter eRBI aRBI aeRatio
Edwin Encarnacion 60.4 107 1.77
Josh Hamilton 72.9 127 1.74
David Ortiz 35.8 60 1.68
Evan Longoria 32.6 53 1.63
Miguel Cabrera 86.3 138 1.60
Jose Bautista 40.0 63 1.58
Ryan Braun 70.7 111 1.57
Giancarlo Stanton 55.3 84 1.52
Alfonso Soriano 71.4 108 1.15
Garret Jones 57.3 85 1.48
An aeRatio above 1 suggests that a player outperformed the average hitter in terms of driving in runs. It is a simple ratio, so a ratio of 1.5 is basically saying that a hitter is producing 1.5 aRBI for each full eRBI he encounters. An aeRatio below one works the opposite way, suggesting a hitter was worse than average and produced a fraction of an aRBI for every eRBI.
Atop our list is the Blue Jays’ newest breakout slugger,
Edwin Encarnacion, who had far and away his best season at the plate. Despite his dominance last season, Encarnacion finished with only 107 aRBI, 30 fewer than
Miguel Cabrera, but you can see that Cabrera had 26 more eRBI, which gave him a clear advantage for the RBI title.
A simple calculation suggests that Encarnacion would have had (1.771 * 86.25 =) 153 RBI if he had been presented with the same opportunities as Cabrera, while the 2012 Triple Crown winner would have only totaled (1.6 * 60.414 =) 97 RBI if he had been given Edwin’s opportunities. I am not suggesting that every single factor would remain the same if the two simply swapped uniforms, but I’m just supplying a method of equalizing players’ RBI totals from one team to another.