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Baseball rewards teams that keep the line moving. The most reliable way to measure that flow is run expectancy. If you want to know how much a base runner changes the scoreboard odds, you need RE24. It takes the context your eyes see on the field and turns it into a clean, fair number. This guide explains RE24 from the ground up, shows how it values base runners, and gives you practical ways to use it for coaching, analysis, and smarter fan debates.
Introduction
Most box-score stats miss the value of a runner on first who goes first to third. They miss the damage a double play does to an inning. They miss how a walk with two on is not the same as a walk with nobody on. Run Expectancy, and the RE24 version especially, fixes that. It answers a simple question in a rigorous way: given the current base and out situation, how many runs should we expect to score by the end of the inning, and how did that change because of this play?
By the end of this article, you will know what RE24 is, how it is built, why it captures the real value of base runners, where it beats traditional stats, and how to use it when making decisions on the field or at the spreadsheet.
What Run Expectancy Is
The base and out frame
In any inning, the bases can be empty or occupied in eight ways, and there can be zero, one, or two outs. That creates 24 base-out states. For each state, we can look across many games and ask how many runs tend to score from that moment until the inning ends. The answer is the run expectancy for that state.
For example, with bases empty and no outs, you can expect roughly half a run to score across modern MLB seasons. With a runner on first and no outs, the expectation rises closer to one run. With the bases loaded and no outs, it jumps above two runs. With two outs, values are much lower because there is less time left in the inning. The exact numbers shift by season and run environment, but the patterns are stable.
How run expectancy tables are built
To build a run expectancy table, you gather every plate appearance in a dataset, track the base-out state at the start, and tally how many runs scored from that point to the end of the frame. Divide total runs by total occurrences for each state, and you get an average. Do that for all 24 states and you have a table you can reference any time a new play happens.
Analysts often use multi-year windows for stability. Teams might use single-season tables to capture current conditions. Both approaches are valid if you interpret them correctly.
From RE to RE24
What RE24 means
RE24 takes the run expectancy table and applies it to every plate appearance credited to a player. It measures how much a hitter or pitcher changes the expected number of runs by what happened during each trip to the plate. You add the changes up across a season to get a total. Positive is good for hitters and baserunners. Negative is good for pitchers.
The simple formula
The logic is straightforward. Before a play, you have a start state with its expected runs. After the play, you have a new state with its expected runs. You also know how many runs crossed the plate during the play. The value of that plate appearance is the runs scored plus the new expected runs minus the old expected runs. Add those values for every plate appearance to get RE24 for that player.
This formula has two advantages. It pays you for the actual runs that score, and it pays you for improving the inning’s future. If you kill the rally, you pay the cost too.
A walk-through example
Say the inning starts with bases empty and no outs. The table says that is worth roughly 0.5 expected runs. The batter hits a single. Now it is a runner on first and no outs, which is worth around 0.9 runs on average. No one scored on the play. The value of the play is 0 plus 0.9 minus 0.5, which equals about 0.4. That credit goes to the batter’s RE24 line. If the next batter hits into a double play, the new state might be bases empty and two outs, worth around 0.1. With no runs scoring, the value is 0 plus 0.1 minus 0.9, which equals minus 0.8 for that batter’s trip. The numbers vary by table, but the method never changes.
Key one-line definitions
RE24 is the sum over a season of the runs added above average by a player, measured by the change in run expectancy during each plate appearance plus any runs that score.
During a plate appearance, RE24 value equals runs scored on the play plus expected runs after the play minus expected runs before the play.
A walk often has higher RE24 with runners on base because it can advance or force runners and raise the next batter’s expected runs beyond the value of a walk with bases empty.
RE24 is context based by base-out state but it is not leverage adjusted by inning or score.
With a runner on first and no outs, a sacrifice bunt often reduces run expectancy in modern MLB.
Why RE24 Captures the Value of Base Runners
Runners shape the inning
Runs are more likely when a team has traffic on the bases. RE24 monetizes that. It gives credit when a batter reaches, when a runner advances, and when an out clears the bases or shortens the inning. Because it compares before and after states, it assigns value to actions that box scores hide, such as taking an extra base or avoiding a double play.
Singles, walks, and who is on ahead of you
Not all singles or walks are equal. With bases empty and two outs, a walk might barely move the needle because the expected runs change very little. With runners on, even a walk can add value by forcing a runner to the next base and raising the next batter’s expectation. A single with a runner on second and one out can be worth more than the same single with two outs and nobody on, because it is more likely to produce a run now and create a stronger next state.
Stolen bases and caught stealing
When a steal succeeds in a good spot, the new state often carries a higher run expectancy. A steal of second with one out usually helps. A steal of third with two outs often does not, because the gain in expected runs from second to third with two outs is small. Getting caught is costly because you lose a runner and move the inning closer to its end. RE24 captures this swing with precision that a simple stolen base percentage cannot.
Double plays, force outs, and outs on the bases
Hitting into a double play hurts because it lowers run expectancy twice at once. It erases a runner and takes the offense two thirds of the way to the inning’s end. Outs on the bases have the same story. They often turn a high-value situation into a low-value one. RE24 quantifies how much value the team lost.
Walks with pressure, walks with space
Base on balls is a tidy illustration. With the bases loaded and one out, a walk adds a run and still leaves runners on for the next hitter, producing a large positive value. With bases empty and two outs, a walk may be modest because one more out ends the frame and there is no runner in scoring position yet. RE24 gives each walk the value it deserves in context.
Comparing RE24 to Other Stats
RE24 vs RBI
RBI counts runs a hitter completes, but it ignores chances where the hitter raised the odds of a later run without being the one to drive it in. It also gives extra credit to hitters who bat behind on-base machines and less to the same hitter in a weak lineup. RE24 assigns value whether the run scores now or later, and it adjusts for what was sitting on the bases when the hitter came up.
RE24 vs wOBA and OPS
Rate stats like wOBA and OPS measure skill in a neutral context. They tell you how often a hitter produces quality outcomes, independent of base-out situations. RE24 is context aware by base and outs. It tells you how much a hitter moved the needle in the spots actually faced. Use both. Rate stats for repeatable skill. RE24 for actual impact across the state mix a player saw.
RE24 vs WPA
Win Probability Added weighs plays by game state. A single that moves win probability 20 percent in the ninth is bigger than the same single in the first. RE24 does not care about inning or score. It only cares about base-out context. That means RE24 is more stable for talent evaluation and WPA highlights clutch moments. RE24 is context based by base-out state but it is not leverage adjusted by inning or score.
Reading a Run Expectancy Table
Key patterns you can trust
No outs is power time. The same base configuration is worth more with fewer outs. Second and third are more dangerous than first and second, which are more dangerous than first and third, but the differences depend on outs. Bases loaded with no outs is a run factory. Bases empty with two outs is not.
Typical modern MLB values offer rough guides. Bases empty, no outs floats near 0.5 runs. Runner on first, no outs sits around 0.9. Runner on second, no outs is a bit above one. Bases loaded, no outs stretches beyond two. With two outs, many states collapse to a few tenths. These shapes are what matter when you compare states before and after a play.
Practical checkpoints for decisions
Ask these simple questions as you watch or coach. Does this action increase the chance of multiple runs or only one? What does it do to the number of remaining outs? Does it remove a high-value runner to chase a small change in position? Does it avoid the double play? Compare the new state’s expected runs to the old state’s. If the difference, plus any runs that score, is positive, that is good RE24.
Using RE24 in Real Decisions
Lineup and roster building
Teams need runners and hitters who can cash them in. RE24 helps you find players who add value across the full spectrum of situations. A hitter with a strong RE24 is not just piling up homers, but regularly improving inning states. Contact skills that avoid double plays will show up. Walks that move runners into scoring position boost totals. On the margins, two hitters with the same OPS can differ by dozens of RE24 runs if one consistently delivers in runner-heavy spots.
In-game tactics
Striking the right balance between risk and reward depends on base-out math. With a runner on first and no outs, bunt attempts often trade a larger run expectancy for a smaller one. With one out and a slow runner on first, a hit and run that avoids a double play can increase the chance of one run while reducing big-inning odds. RE24 keeps you honest by measuring the actual change from the attempt, not the intention.
Baserunning aggression
Go first to third on a single with one out and your offense grows. Try to steal third with two outs and you often risk more than you gain. Tag from third on a medium fly with one out and you score now but remove the chance for a larger inning if you are out at the plate. RE24 crystalizes these choices. The best runners add value not only by being fast but by picking the right moments to gamble.
Pitching and defense
Pitchers and fielders can manage innings proactively. Avoiding walks with two outs has a smaller RE benefit than avoiding walks with no outs, but double plays flip states fast in your favor. Controlling the running game prevents low-risk steals that bump run expectancy in quiet ways. A strikeout with runners on base protects against balls in play that jump RE. Allowing an extra base on a misplay can cost you more value than the box score suggests.
Case Studies: RE24 in Action
Leadoff walk with a power bat behind
Start with bases empty and no outs at roughly 0.5 expected runs. The hitter draws a walk. Runner on first and no outs lives near 0.9. The plate appearance value is about 0.4. If the next hitter doubles and the runner scores, add the run plus the new state. Say it becomes a runner on second with no outs at around 1.1. The value of that double is 1 plus 1.1 minus 0.9, about 1.2. Both hitters get full credit for their part of the inning’s growth.
Productive out vs run value
Man on first, no outs. The team bunts the runner to second, creating one out with a runner on second. If the new state has a lower expected run value than the original state, the play costs value, even if it feels like momentum. The numbers change by era and team quality, but in many settings that sacrifice trade is negative in RE24. If the follow-up is a single that scores a run, that hitter gets big positive value. The bunt’s negative value does not disappear.
Reliever stranding runners
A reliever enters with a runner on third and one out. Suppose the expected runs sit around 0.9. The reliever gets a strikeout and a groundout, inning over. The final state has zero expected runs, and zero runs scored. The reliever’s RE24 for that outing is 0 plus 0 minus 0.9, which equals minus 0.9 for the offense and a strong positive contribution for the pitcher. Stranding runners produces large RE gains for pitchers because they shrink the inning’s potential sharply.
Building Your Own RE Table
Data you need
You need a play-by-play log that tracks base runners, outs, and runs scored to the end of each inning. For each plate appearance, mark the start state. From that moment to the inning’s end, count how many runs score. Average those counts within each of the 24 states. Store the results in a table keyed by base-out state.
Season-specific vs multi-year
Single-season tables reflect current run environments, ballparks, and baseballs. Multi-year tables offer smoother estimates with less noise. Use season-specific tables if you want precision for that year. Use multi-year if you want stability and if your sample is small. Whichever you choose, apply the same table consistently when you calculate RE24 to avoid mixing baselines.
Limits and Common Pitfalls
Park and era effects
Run expectancy depends on how easy it is to score. High-altitude parks inflate values. Run-suppressed eras deflate them. If you compare players across seasons or stadiums using one fixed table, you can misread value. Either park-adjust or at least compare players to peers within the same environment.
Not leverage adjusted
RE24 is context based by base-out state but it is not leverage adjusted by inning or score. That is a feature for skill evaluation but a limitation for storylines. Keep WPA nearby if you want to measure high-pressure swings in win probability.
Score effects and late innings
Teams change tactics with big leads or in tight late innings. They may bunt more, pitch around more, or defend differently. A generic RE table does not fully capture these behavior shifts. If you care about those, you can build split tables by inning or game state, but you will trade precision for smaller samples.
How RE24 Changes Player Evaluation
Hitters
Hitters who avoid double plays, work walks with men on, and add bases on balls in play often post strong RE24 even without elite slugging. Sluggers who cluster events with bases empty can have fewer RE24 spikes than their raw power suggests. Balanced hitters tend to show steady RE24 because they consistently upgrade the inning’s state.
Baserunners
Stolen base totals are less important than the timing and the base-out state. Taking third with one out is better than taking third with two outs. First-to-third on singles adds more value than a cautious stop at second. Smart baserunners show up in RE24 by helping hitters get larger post-play states.
Pitchers
Pitchers surface in RE24 when they suppress rallies. Strikeouts with men on protect against balls in play that would push expected runs up. Inducing grounders with a runner on first and one out can yield double plays that collapse the inning’s run expectancy. Free passes and hit batters inflate it.
Practical Workflow for Analysts and Coaches
Use a fresh run expectancy table
Grab a recent table that matches your level of play. High school, college, minor leagues, and MLB have different scoring environments. Use the right baseline. Check a few anchor values first. Runner on first, no outs should be close to one run. Bases loaded, no outs should be above two.
Tag every plate appearance
Record the start state, the result, any runs that score, and the end state. Calculate the play value. Sum by players, by innings, by games. The process is simple and repeatable.
Review by situation
Break summaries by base-out state. Which hitters crush with runners on second and third. Which hitters create too many double plays. Which runners deliver extra bases in low-risk spots. Which pitchers strand runners. The shape of contribution matters as much as the total.
Coaching Tips Based on RE24
Guard against the double play
With a runner on first and less than two outs, double plays are inning killers. Favor line drives and fly ball profiles in that spot if your personnel allow it. Consider hit and run with contact hitters to keep infielders moving.
Choose steals with a purpose
Steal second with one out if success rates are high. Be cautious with two outs and third base. The expected gain is smaller and the cost of an out is severe. Let your best hitters swing when the base-out state is already rich.
Be skeptical of early bunts
Trading an out for one base often reduces expected runs with no outs. Unless you are playing for a single run, it is usually not worth it. With weaker hitters up and high double play risk, the calculus can change. Let the table guide, not ideology.
Takeaways You Can Apply Today
Think in base-out states. Assign value by how a play changes the inning. Praise hitters and runners who raise expected runs and avoid the traps that lower it. Reward pitchers who shrink expected runs when it matters most. Use RE24 as your reality check on tactics like bunts and steals. Learn the few anchor values for your level and compare before and after on every play you care about.
Conclusion
RE24 turns the chaos of an inning into a clean and honest accounting sheet. It captures the value of base runners, the harm of double plays, and the hidden gains from smart aggression. It is not a replacement for every stat, but it fills a gap that box scores leave open. If you want to evaluate players by what their trips to the plate actually did to the inning’s future, use RE24. If you want to coach cleaner decisions, base them on changes in run expectancy. Start with a reliable table, apply the simple formula, and let the numbers tell you which actions truly build innings.
FAQ
Q: What is RE24 in one sentence?
A: RE24 is the sum over a season of the runs added above average by a player, measured by the change in run expectancy during each plate appearance plus any runs that score.
Q: How is RE24 calculated during a plate appearance?
A: During a plate appearance, RE24 value equals runs scored on the play plus expected runs after the play minus expected runs before the play.
Q: Why can a walk be more valuable with runners on base?
A: A walk often has higher RE24 with runners on base because it can advance or force runners and raise the next batter’s expected runs beyond the value of a walk with bases empty.
Q: Does RE24 account for leverage like inning and score?
A: RE24 is context based by base-out state but it is not leverage adjusted by inning or score.
Q: Do sacrifice bunts often help with a runner on first and no outs?
A: With a runner on first and no outs, a sacrifice bunt often reduces run expectancy in modern MLB.