Understanding ERA in Diamond Analytics
What is ERA?
Earned Run Average (ERA) measures how many earned runs a pitcher allows per game. Lower is better.
Standard ERA Formula
ERA = (Earned Runs ÷ Innings Pitched) × Game Innings
Age-Appropriate Calculation
Diamond Analytics adjusts ERA based on your team level because youth games use fewer innings than professional baseball:
| Level | Game Innings | ERA Formula |
|---|---|---|
| 8U – 12U | 6 innings | (ER ÷ IP) × 6 |
| 13U – 18U | 7 innings | (ER ÷ IP) × 7 |
| Middle School | 7 innings | (ER ÷ IP) × 7 |
| High School | 7 innings | (ER ÷ IP) × 7 |
The ERA label throughout the app indicates which calculation is being used — for example ERA (6-inn) or ERA (7-inn).
Why This Matters
A pitcher who allows 2 earned runs over 3 innings has:
- Standard (9-inn) ERA: 6.00
- Youth 7-inn ERA: 4.67
- Youth 6-inn ERA: 4.00
Using age-appropriate innings gives a more accurate picture of performance relative to the game format actually being played.
Earned vs Unearned Runs
Only earned runs count toward ERA. Runs that score due to errors are unearned and do not count. When logging pitching data, earnedRuns is recorded separately from total runs allowed.