aeRatio
A true measure of RBI

Powered by thePhaithful.com

Players Team Position

Season Name PA eRBI AB eRBI aRBI ROLA aeRatio

Season Team Battling Order Spot eRBI
Description Glossary

Statistic Description

With each player coming up to the plate over the course of a year, they will all have unique situations due to their spot in the lineup and surrounding teammates. Some players are faced with more opportunities to drive in runs than others, some RBI are driven in easier than other RBI, and some players just have more total at bats in general--so why should a player’s ability to drive in runs be measured by only a simple tally of the runners they cause to score? By creating the measure of Expected RBI, you are able to find how well a player drives in runs in relation to the situations that they were presented.

In order to do so, you need to calculate:

Using Retrosheet, all of the above data is available to calculate.  Multiplying the outcome percentages with the RBI created percentages by the number of ABs in a given situation will give you a player’s expected RBI for that situation.  Repeat for each situation for their total expected RBI that season.

Also using Retrosheet, you can find a players actual RBI in each of these situations during a season.  Once a total actual RBI and expected RBI are found for a player, simply divide the actual RBI by expected RBI to get their aeRatio, or take the difference

Please refer to the links and the glossary for any further explanation.  Also, I will be adding an expansion page as I include tips and enhancements in the future.


Glossary

eRBI – Expected RBI

Represents how much RBI a league average player would have generated in a specific set of situations.

aRBI – Actual RBI

Represents the number of runners that a player drove in during an at bat, which eliminates RBIs accumulated on walks or errors in the field - sacrifice flies and groundouts are still included.

AB eRBI - eRBI Accumulated in At Bats

Represents opportunity that a player gets during a plate appearance that ends in an outcome that qualifies as an at-bat.

PA eRBI - eRBI Accumulated in Plate Appearances

Represents opportunity that a player gets in every plate appearance, regardless of the outcome.

TeamSpot eRBI - eRBI Accumulated by Line Up Position

Represents opportunity that a spot in a team's batting order is given to drive in runs, regardless of the batter or the outcome of the plate appearance.

aeRatio – Actual RBI over Expected RBI

Represents the amount of actual RBI that a player earns per each expected RBI. A ratio above one shows a player drove in more runs than expected, while a ratio under one shows a player failed to drive in more runs than what the league average would be expected to.

ROLA – Runs Over League Average

Represents the variance between a player’s actual RBI and their expected RBI. A positive ROLA shows a player who drove in more runs than expected, while a negative ROLA shows a player failed to drive in more runs than what the league average would be expected to.

Additional Notes

  • Players must have accumulated at least 20 eRBI to be considered
  • Only non pitchers are eligible
  • League averages exclude all pitchers ABs except when they are pinch hitting



    • the 24 Base Out States

    0 out 1 out 2 out
    --- --- ---
    x-- x-- x--
    -x- -x- -x-
    --x --x --x
    xx- xx- xx-
    x-x x-x x-x
    -xx -xx -xx
    xxx xxx xxx
    -top-

    At Bat Outcomes

    Single Groundout
    Double Flyout
    Triple Fielders Choice
    Homerun Strikeout

    * Walks, HBP, IBB, sac bunts do not qualify as ABs
    * Errors qualify as ABs, but are not used for aRBIs
    -top-

    League Average Outcomes

    2008 2007 2006 2005 2004 2003
    1B 17.64% 17.75% 17.85% 17.68% 17.61% 17.57%
    2B 5.64% 5.5% 5.54% 5.41% 5.4% 5.38%
    3B 0.54% 0.56% 0.58% 0.54% 0.55% 0.57%
    HR 2.99% 2.99% 3.29% 3.09% 3.33% 3.19%
    GO 26.58% 27.43% 27.01% 27.66% 27.38% 27.72%
    FO 27.45% 27.43% 27.53% 27.85% 27.42% 27.75%
    K 19.04% 18.34% 18.21% 17.78% 18.32% 17.82%
    -top-