Hong Life CalculatorsUnderstanding the stolen base success rate and break-even calculator — concept and principle
A stolen base gains a base, but getting caught costs an out and removes a runner, which hurts much more. This calculator shows a runner's success rate, compares it with the typical break-even rate, and estimates the net runs gained or lost using average run values for a steal and a caught stealing.
How it is calculated
- Success rate = SB / (SB + CS) × 100.
- Net runs = 0.2 × SB − 0.41 × CS, using about +0.2 runs per successful steal and −0.41 runs per caught stealing.
- Break-even rate is the success rate at which net runs are zero: p × gain = (1 − p) × cost, so p = cost / (gain + cost).
With the weights used here, p = 0.41 / (0.2 + 0.41) ≈ 67%. The calculator shows this value, 67.21%; the commonly quoted 70–75% reflects older run environments and the situations where most steals happen.
The principle
The values come from run expectancy: the average runs a team scores from each base-out state until the end of the inning. Moving from first to second with no one out raises run expectancy slightly, but being thrown out turns "runner on first, no outs" into "bases empty, one out", which costs far more. Because the loss is about twice the gain, a runner must succeed roughly two times out of three just to break even. The exact figures depend on the inning, score, outs, the base being stolen and the league's scoring level.
Worked example
- Inputs: 30 SB, 8 CS.
- Success rate = 30 / 38 = 78.95%.
- Gain from steals = 30 × 0.2 = 6.00 runs; cost of caught stealing = 8 × 0.41 = 3.28 runs.
- Net runs = 6.00 − 3.28 = +2.72.
- 78.95% is above both 67% and the 70–75% guideline, so the running added value.
| Stolen bases | Success rate |
|---|---|
| 7.5 | 48.39% |
| 15 | 65.22% |
| 22.5 | 73.77% |
| 30 | 78.95% |
| 37.5 | 82.42% |
| 45 | 84.91% |
| 60 | 88.24% |
How to read the result
A positive net-run total means stealing helped the team; a negative one means the runner would have done better staying put. Since roughly 10 runs equal one win in modern baseball, +2.72 runs is worth about a quarter of a win. Elite base stealers often succeed 80% of the time or more. Success near 60% is usually a net loss even if the stolen-base total looks impressive.
Common mistakes
- Judging a runner by stolen bases alone without counting caught stealing.
- Ignoring the game situation; stealing third with two outs or when far behind changes the value.
- Forgetting that pickoffs also cost outs and are not part of these inputs.
Frequently asked questions
Why is caught stealing so costly?
It removes a baserunner and adds an out at the same time, and outs are the scarcest resource in an inning.
Is the break-even rate the same for stealing third?
No. It depends on the number of outs and the base; tables in The Book give different values for each case.
Did recent rule changes affect stealing?
MLB's 2023 changes (bigger bases and limits on pickoff attempts and step-offs) increased attempts and success rates.
Sources: Tom Tango, Mitchel Lichtman and Andrew Dolphin, The Book: Playing the Percentages in Baseball (2007) · John Thorn and Pete Palmer, The Hidden Game of Baseball (1984)