What is Secondary Average? Definition, Formula, and Example
Secondary average measures everything a hitter contributes beyond batting average — walks, extra-base power, and stolen bases — in a single number scaled like a batting average.
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What is Secondary Average?
Secondary average (SecA) is a Bill James statistic that captures all the offensive value a hitter produces that batting average ignores: walks, extra bases on hits, and stolen bases. Two hitters can both bat .260 and be wildly different offensive players — one a slap singles hitter, the other a walk-drawing slugger. Secondary average quantifies that gap. It's scaled to look like a batting average, so a .400 SecA is elite and a .150 SecA is punchless.
How is Secondary Average Calculated?
The formula:
SecA = (BB − SO... no — the canonical James formula is:
SecA = (BB + (TB − H) + SB) ÷ AB
That is: walks, plus total bases minus hits (the extra bases beyond singles), plus stolen bases, all divided by at-bats. Some modern versions subtract caught stealings. Benchmarks:
- .500+ — elite (Bonds, prime Trout territory)
- .350–.450 — strong secondary production
- .200–.250 — league average
- Under .150 — empty-average hitter
A Real-World Example
Kyle Schwarber is the patron saint of secondary average. In 2023 he hit .197 — a batting average that looks unplayable — but drew 126 walks and hit 47 home runs. His SecA was roughly .500, an elite figure that explains why his wRC+ was comfortably above average despite the sub-.200 average. The mirror image is a contact hitter like 2022 Amed Rosario: a .283 batting average but a SecA near .180, because he walked rarely and hit few homers. Same-looking "good hitter" by average, drastically different actual value — SecA exposes it instantly.
Why Secondary Average Matters
SecA is a fast diagnostic for whether a batting average is *real*. A prospect hitting .290 in the minors with a .150 SecA has a hollow profile that collapses against MLB pitching; a .240 hitter with a .400 SecA has the plate discipline and power foundation that survives promotion. Fantasy players use it to find batting-average bargains — hitters whose value in OBP or points formats far exceeds their roto price. It also pairs naturally with ISO: ISO isolates power, SecA folds in walks and speed for the fuller picture.
Limitations and Misconceptions
Secondary average is descriptive, not run-valued — it doesn't weight walks versus extra bases by actual run contribution the way wOBA does. Stolen bases inflate it in ways that matter little to run scoring (a 40-steal burner gets a big SecA bump). And it deliberately excludes batting average, so two hitters with identical SecA can still differ hugely in value through their singles rate. It's a complement to average, never a replacement. Don't confuse it with slugging percentage, which counts singles and ignores walks entirely.
Related Terms
In Legends Deck: Secondary average feeds the non-contact outcome weights on hitter cards — Schwarber-style cards draw walks and produce extra bases at elite rates in simulation even when their simulated batting average craters, making them far more valuable in-game than their average suggests. Sort your collection by SecA to find hidden gems.