What is a Stolen Base? Definition, Formula, and Example
A stolen base is credited when a baserunner advances to the next base on his own — without a hit, walk, error, or other event forcing the advance — usually by breaking for the base as the pitcher delivers.
What Is a Stolen Base in Baseball?
A stolen base (SB) is awarded when a baserunner successfully advances to the next base under his own power, without being forced there by a hit, walk, error, fielder's choice, balk, or wild pitch. In practice, the runner takes a lead, then breaks for the next base the instant the pitcher commits to the plate, trying to reach it before the catcher's throw arrives. If the throw beats him and he's tagged out, he is charged with a caught stealing (CS) instead. Stealing second base is the most common; stealing third is rarer and riskier; stealing home is a rare, high-difficulty play. The skill is a blend of raw speed, jump-timing off the pitcher, and a read on the pitcher's delivery and the catcher's pop time.
How Stolen Bases Are Scored and Measured
There's no formula for a single stolen base — the official scorer credits one each time a runner advances cleanly on his own. What matters for evaluation is stolen base success rate, the percentage of attempts that succeed:
SB% = Stolen Bases ÷ (Stolen Bases + Caught Stealing)
Because a caught stealing erases a baserunner and an out is the game's scarcest resource, analysts generally consider a runner needs to succeed about 75% of the time to add net value. Below that break-even point, the outs given away outweigh the bases gained.
Worked Example
Ronald Acuña Jr.'s 2023 MVP season is the modern benchmark. He stole 73 bases and was caught 14 times, for a success rate of:
73 ÷ (73 + 14) = 73 ÷ 87 = 83.9%
That total made him the first player in MLB history to record at least 40 home runs and 70 stolen bases in a single season. His 83.9% clip sailed well past the 75% break-even line, meaning his running was a clear net positive, not empty volume. The 2023 rule changes — larger bases and a limit of two pickoff attempts (disengagements) per plate appearance — pushed league-wide success rates near 80%, the highest in modern history, and revived the stolen base as a strategic weapon.
Why Stolen Bases Matter
Stolen bases drive run expectancy by moving a runner into scoring position without spending an out, turning a single into a near-double on the bases. In fantasy and DFS, SB is one of the five standard rotisserie hitting categories, making elite base-stealers like Acuña and Elly De La Cruz scarce, valuable roster pieces. For front offices, a high success rate signals a runner who reads pitchers well — not just one who runs fast.
Limitations and Common Misconceptions
The biggest misconception is that raw steal totals equal value. A player with 40 steals and 25 caught stealings (62%) is actively hurting his team despite the gaudy number, while a runner with 25 steals and 2 caught (93%) is far more productive. Stolen bases also don't capture all of baserunning value — taking the extra base on a hit, going first-to-third, and avoiding outs on the bases are measured separately by BsR. Finally, sprint speed and stolen bases are related but distinct: plenty of fast players rarely run, and some savvy base-stealers post elite success rates on average speed by getting great jumps.
In Legends Deck: a card's speed and baserunning ratings draw on both Statcast sprint speed and stolen base success rate, so the simulation rewards efficient runners who pick their spots — a card that steals at a high clip generates extra scoring chances, while a reckless runner with a low success rate gets thrown out and kills rallies, just like the real thing under the pitch clock era's revived running game.