Isolated Power (ISO), Explained: Raw Power Without the Singles
Isolated Power strips singles out of slugging to leave pure extra-base pop. Across 2024's 30 teams, ISO tracked homers at r=0.95 but scoring at just 0.86.
Category
Stat Explainers
The metrics, demystified. Plain-English explainers of the numbers that describe baseball — what each stat measures, its formula, and when to reach for it.
Linear Weights, Explained: Why a Double Isn't Worth Two Singles
A double isn't worth two singles, and the run-expectancy math says exactly why. How linear weights turn each event into a run value, and how they quietly power wOBA.
Bat Speed and Bat Tracking, Explained: Inside Statcast's Swing Metrics
Statcast now clocks the swing itself. What bat speed, swing length, and squared-up rate measure, and why bat speed trades off against making contact.
Catcher Pop Time, Explained: The Two Seconds That Stop a Steal
Glove to glove in about two seconds. How Statcast measures catcher pop time, why the transfer and the throw are separate skills, and what makes a sub-2.0 elite.
Platoon Splits, Explained: Why Lefty-on-Lefty Favors the Pitcher
Same-handed matchups tilt toward the pitcher, and rosters are built to exploit it. What drives the platoon advantage, and why small platoon samples lie.
Run Expectancy and RE24: Valuing Every Base-Out State
Every base-out state has an expected run value. How the run-expectancy matrix and RE24 turn game states into numbers — the engine behind modern strategy.
BaseRuns and Cluster Luck: Why Run Totals Don't Match the Parts
A team's runs depend on when its hits cluster, not just how many it gets. How BaseRuns estimates what a lineup should have scored, and what luck hides.
Sprint Speed, Pop Time, and Arm Strength: Statcast's Athleticism Metrics
Statcast doesn't just measure outcomes — it clocks raw tools. What sprint speed, pop time, and arm strength actually measure, and what counts as elite.
DRS vs. OAA: Two Ways to Measure a Defense
Defensive Runs Saved and Outs Above Average both grade gloves in runs, and they don't always agree. How each is built, why they diverge, and which to trust.
Pitch Framing, Explained: How Catchers Steal Strikes
A called strike or ball is one of baseball's biggest hidden swings. How catchers steal strikes, how framing runs are measured, and what robot umps would do.
WPA and Leverage Index: Measuring the Drama, Not Just the Value
Win Probability Added and Leverage Index put a number on the moment. What they measure, and why they're built for storytelling rather than projecting.
Park Factors Explained: How Coors Field and the Green Monster Warp the Stats
Coors inflates offense; pitchers' parks suppress it. What a park factor is, how it's computed, and how stats like OPS+ and wRC+ use it to level the field.
Stuff+, Location+, and Pitching+: Grading a Pitch Before Anyone Swings
A new family of models grades a pitch on its physical traits alone, before the result. What Stuff+, Location+, and Pitching+ measure, and why 100 is average.
FIP and xFIP Explained: Judging Pitchers Beyond ERA
ERA blames pitchers for things they don't control; FIP and xFIP focus on what they do. The formulas, the FIP constant, and judging pitchers beyond runs.
xBA, xSLG, and xwOBA: A Practical Guide to Expected Stats
xBA, xSLG, and xwOBA strip luck out of the box score. What expected stats measure, where they fail, and how to spot over- and under-performers.
Why WAR Is Calculated Differently on Different Sites
Baseball-Reference and FanGraphs publish different WAR for the same player. Exactly why the two versions diverge — and how to use both without losing your mind.
Outs Above Average: How Statcast Grades Defense
Outs Above Average is Statcast's range-based defensive metric. How it works, what counts as a good number, and who graded out best with the glove in 2025.
Barrel Rate Explained: The Statcast Metric That Predicts Power
Not all hard contact is equal. How Statcast defines a 'barrel,' why barrel rate predicts power better than exit velocity alone, and how to read it.
BABIP Explained: Luck, Skill, and Balls in Play
Batting average on balls in play separates luck from skill — and flags which hitters are due to regress. What BABIP measures, and why .300 is the number to know.
OPS+ vs. wRC+: What's the Difference and Which Should You Use?
Two park- and league-adjusted hitting stats, two scales, one common confusion. When OPS+ and wRC+ disagree — and which one belongs in your analysis.
What Is wOBA? Why It Beats Batting Average
Batting average treats every hit the same; weighted on-base average doesn't. The formula, the weights behind it, and why wOBA is the better one-number snapshot.