What is Speed Score? Definition, Formula, and Example
Speed score (Spd) is a Bill James statistic that rates a player's raw speed on a 0–10 scale using stolen bases, triples, runs scored, and double-play avoidance.
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What is Speed Score?
Speed score (Spd) is a Bill James invention, now published by FanGraphs, that estimates how fast a player actually is using only box-score statistics — no stopwatch or tracking data required. It runs on a 0–10 scale where 5 is league average, 7+ is a genuine burner, and anything below 3 belongs to catchers and first-base sluggers. In the Statcast era it functions as a sanity check against sprint speed, and it remains useful for evaluating minor leaguers and historical players who have no tracking data.
How is Speed Score Calculated?
Speed score averages four component scores, each scaled 0–10:
1. Stolen base percentage — success rate rewards efficient runners.
2. Stolen base attempt frequency — how often a player runs when he reaches first.
3. Triples rate — triples divided by balls in play; triples are the purest speed outcome in the box score.
4. Runs scored rate — runs as a percentage of times on base, capturing the ability to score from first on a double and take extra bases.
The four scores are averaged into the final Spd. FanGraphs leaderboards treat 7.0+ as elite, 4.5–5.5 as average, and under 3.0 as slow.
A Real-World Example
Billy Hamilton, the fastest player of his generation, posted speed scores in the 9.5+ range during his peak — 59 steals in 2014, triples galore, runs scored on anything hit to the gaps. On the modern leaderboard, Elly De La Cruz runs Spd marks above 8.0, matching his 30+ ft/sec Statcast sprint speed. At the bottom, a slow-footed slugger like Daniel Vogelbach sits near 1.5 — essentially never stealing, never legging out a triple, station-to-station on the bases. The scale maps cleanly to what the eye test and tracking data confirm.
Why Speed Score Matters
Speed is the tool that ages worst and translates most directly to defense and baserunning value. Front offices use Spd as a quick screen on minor leaguers, where no sprint-speed data exists — a shortstop with a 7.5 Spd in Double-A has the wheels to stay up the middle; one at 4.0 is moving to a corner. Fantasy players in roto leagues use it to project stolen bases beyond raw SB totals, since attempt frequency and triples rate reveal willingness and ability that raw totals miss. It also feeds BsR baserunning value as a sanity check.
Limitations and Misconceptions
Speed score measures *statistical outcomes*, not raw velocity — a smart, aggressive runner with average wheels (think prime Dustin Pedroia) can post a misleadingly high Spd, while a fast player on a conservative team that never lets him run looks slower than he is. It also conflates opportunity with ability: runs-scored rate depends on the lineup hitting behind you. For current MLB players, sprint speed is strictly better; Spd's real value is historical comparison and minor league evaluation. Don't confuse it with stolen base totals alone — Spd deliberately punishes slow players who never attempt.
Related Terms
In Legends Deck: Speed score calibrates the baserunning engine behind every card — high-Spd cards take the extra base on simulated hits, steal more aggressively, and beat out more infield grounders, while low-Spd cards clog the bases exactly like their real-world counterparts. Check Spd before you send the runner.