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
DRS and Outs Above Average both grade gloves in runs and don't always agree, which is also why Baseball-Reference and FanGraphs publish different WAR.
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.
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.
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.
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.
xBA, xSLG, and xwOBA: A Practical Guide to Expected Stats
What xSLG, xBA and xwOBA mean: Statcast's expected slugging and batting average from exit velocity and launch angle, the 2025 gap leaders, and where they mislead.
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.
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.
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.