Get to Know: RE24

RE24 (runs above average by the 24 base/out states): RE24 is the difference in run expectancy (RE) between the start of the play and the end of the play. That difference is then credited/debited to the batter and the pitcher. Over the course of the season, each players’ RE24 for individual plays is added up to get his season total RE24.

Calculation Example
: In game 4 of the 2007 World Series, the RE for the Red Sox to start the inning was .52. When Jacoby Ellsbury doubled off Aaron Cook in the very first at-bat in the game, the Red Sox were then expected to score 1.15 runs for the rest of the inning. The difference or RE24 was .63 runs. Ellsbury was credited +.63 runs and Aaron Cook credited with -.63 runs.

Why you should care: RE24 tells you how many runs a player contributed to his team. It’s similar to WPA (except in runs), but unlike WPA it does not take into account the inning or score of the game. Therefore, it is a more context neutral statistic. It does however take into account how many runners are on base and how many outs are left in the inning.

Variations: REW (run expectancy wins) is RE24 converted to wins.

Links and Resources:

Run Expectancy by Run Environment
The Book Wiki: Run Expectancy




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David Appelman is the creator of FanGraphs.


15 Responses to “Get to Know: RE24”

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  1. Samg says:

    What about REW/boLI?

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  2. Peter Jensen says:

    What RE table are you using to calculate the stat? RE for each individual year, by league, or an accumulation of years?

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  3. Ian A. says:

    Here’s a question that has bothered me for a while regarding RE24.

    If there is a runner on second with two outs, according to “The Book”, you have an RE of 0.325. If the batter hits a single, scoring the runner, the new RE is 0.216.

    RE24 would have a pretty glaring flaw if there isn’t something to account for the runner scoring, thus reducing the RE according to base/out states. I would hate to think such a useful statistic could be so easily flummoxed.

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    • zacksf says:

      So then the batter is credited with: (1-.325) + .216 .
      The first term for the run scored, the second term for creating the additional runner (himself). Is that correct?

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      • CJ says:

        Yeah, so it’s the ‘runs expected’. You score the one run you have (you’ve banked it) plus you’re expected to score another 0.216 runs.

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  4. Ian A. says:

    Answered my own question by emailing the authors of “The Book”

    “Yes, you have to add 1 for each run.

    http://www.tangotiger.net/lwbymob.htm

    Tom”

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  5. Ken Williams says:

    I love the RE24 stat but have a problem with the way runs are credited. Why does the value of the run(s) scored on a given play go entirely to the batter? If the leadoff hitter singles, steals second, steals third, and then scores on a weak groundball to second, why does the value of the run go to the batter? It should be split between the two because the run could not have scored without each player doing their part.

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    • zacksf says:

      The RE is already high with the runner on 3rd. The batter only gets the difference between that and 1, or really, 1-RE(before ground out). Does that make sense?

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    • zacksf says:

      Here is a more specific response, though the numbers are guessed.

      Inning begins: Re=.5
      Batter singles: Re=.9 (+.4 credit)
      steals 2nd: Re=1.1 (+.2 credit)
      steals 3rd: Re=1.4 (+.3 credit)
      ground ball
      to 2nd, run
      scores, 1 out Re=.3 (-.1 credit, calculated as 1.4-0.3 + 1)

      So even with the +1 credit the 2nd batter has a net negative RE credit for adding the out and dropping the RE by 1.1.

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      • zacksf says:

        So the leadoff hitter gets a +.9 in the above example, the 2nd batter, who got the RBI, actually gets a -0.1 (negative) in this case. I believe it would have been positive had it been a runner on 3rd and 1 out.

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        • Jason says:

          What I’d like to know is there any metric to acount for a baserunner doing a good job of moving up?

          For example:

          Runner on 1st, 1 out. RE = 0.51

          Batter hits a single, good baserunner moves to 3rd.
          Runners on 1st & 3rd. RE = 1.15, batter “earns” 0.64

          Batter hits a single, slow runner only moves to 2nd.
          Runners on 1st & 2nd. RE = 0.90, batter “earns” 0.39

          So there’s a 0.25 run difference there. There’s a ton of problems to consider here; whether or not the runner moves up obviously depends on how the ball is fielded, the read the runner gets, the speed of the runner, and how and where the ball was hit. I can imagine that with a large enough sample that we could assume the effects of the hitter and fielder even out and that there is an average rate at which a runner should make it from 1st to 3rd. Given all that, would individual players be in situations like that enough that making adjustments would be informative, i.e. would a good runner have enough opportunities to take an extra base that the sample size for his opportunities would be big enough?

          Also, if the runner gets thrown out at 3rd as above,
          Runner on 1st, 2 outs. RE = 0.22, batter “loses” 0.29

          You get a swing of 0.93 there if the runner is safe at 3rd instead of out.

          I’m not sure how I feel about that, because like any other statistic we just have to hope that those events even out in the end and I think it’s a complex event involving the fielder and runner that there’s likely not a solid way to make easy and objective measurements.

          That’s using 2012 expectancies from BR.

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    • John Thacker says:

      Are you okay with the existing idea in baseball that a batter does not get an RBI for a run scoring on a double play? Even though “the run could not have scored without each player doing their part?”

      Baseball has long understood that a particular batter’s outcome can be so bad that he didn’t really help, despite the run scoring. This is the same sort of thing, except a little more precise and distinguishing between different situations more.

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  6. zacksf says:

    So does RE24 have the same “units” as RBI (and runs)

    Is it fair to say that:
    wOBA is a more sophisticated version of on base percentage (or OPS),
    and
    RE24 is a more sophisticated version of RBI or perhaps RBI+runs?

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