SportStatNow

Guides

Deeper explainers behind the stats — what a formula actually measures, why it's calculated that way, and what counts as good. Every guide cites its sources and links to the calculator that runs the math for you.

What Is a Good ERA? How to Read the Number

ERA bands for starters vs. relievers, why league-average ERA shifts year to year, and the two well-documented limitations of the stat.

Read guide →How Is NFL Passer Rating Calculated? The Formula Explained

Why passer rating uses those specific baselines and a 158.3 ceiling, what it deliberately leaves out (sacks, rushing), and how it differs from ESPN's QBR.

Read guide →True Shooting % vs. Field Goal %: What's the Real Difference?

A side-by-side worked example showing how two players with identical field goal percentage can have a 25+ point gap in true shooting percentage.

Read guide →What Is a Good Save Percentage in Hockey?

SV% bands for NHL starting goaltenders, why the stat can't see shot quality, and why shootout attempts are excluded entirely.

Read guide →Handicap Index vs. Course Handicap: What's the Difference?

Handicap Index describes your general ability; Course Handicap adjusts it for one specific course. Here's exactly how WHS converts one into the other.

Read guide →How Is Clean Sheet Percentage Calculated?

The formula, why sources disagree on substitute appearances, and what counts as a good clean sheet rate at the professional level.

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