GUIDES · BETSLIP DOCTOR
How can a pitcher allow runs without all of them increasing ERA?
ERA uses earned runs rather than every run on the scoreboard. When an error or passed ball affects the inning, the official scorer judges whether a run would have scored without that defensive mishap; an unearned run does not enter the pitcher's ERA.
For Bettors and cappers learning to read baseball records · Updated
The scorer evaluates the run, not just the final score
MLB defines an earned run as one that scores without the benefit of an error or passed ball. An unearned run is tied to an error or passed ball, and the official scorer may need to judge whether the run would have scored without it.
That judgment is why a pitcher can be charged with a team run while the run is excluded from the earned-run total.
ERA uses only the earned-run count
ERA is nine times earned runs divided by innings pitched. If a pitcher leaves runners on base, earned runs scored by those runners can still be charged to that pitcher.
A line showing runs allowed and a line showing earned runs are different records. Do not assume every run scored during an appearance is earned.
Hypothetical inning reconstruction
Fictional sequence: with two outs, a batter reaches on a fielder's error; a later hit brings that runner home. Reconstruct the inning without the error: if the scorer determines the third out would have ended the inning before the later hit and run, that run is unearned. If the pitcher also allowed two earned runs in six innings elsewhere in the line, ERA is 9 × 2 ÷ 6 = 3.00, even though three total runs scored.
Related questions
Does every run after an error become unearned?
Not automatically. The official scorer determines whether the run would have scored without the error or passed ball.
Are unearned runs included in ERA?
No. MLB's ERA formula uses earned runs divided by innings pitched, scaled to nine innings.