Run values: pricing every event
What is a walk actually worth? Not vibes — a number.
Take millions of real innings and ask: on average, how many runs eventually score after each event, in each situation? Do the accounting and every baseball event gets a price tag in runs — a linear weight.
The modern price list (roughly)
Walk ≈ +0.3 runs. Single ≈ +0.45. Double ≈ +0.75. Triple ≈ +1.05. Homer ≈ +1.4. An out ≈ −0.26. Two things jump out: a homer is worth ~3 singles (not 4 — sorry, SLG), and outs are genuinely expensive, which is why OBP matters so much.
This one idea is the engine under everything modern: wOBA prices a hitter's events (next lesson), FIP prices a pitcher's K/BB/HR, and Statcast run values price individual pitches. Learn the price list once and half of sabermetrics becomes 'multiply and add'.
How this stat lies to you
- These are AVERAGE values — a 9th-inning walk in a tie game is worth more than these numbers say (that's WPA, Level 5).
- Prices drift with the run environment; 2000s weights differ slightly from today's.
- Linear weights assume events add up independently — mostly true, not perfectly.
Check yourself
1. Per run values, roughly how many singles equal one home run?
2. Why are outs 'expensive' in this framework?