HR/9
Home runs allowed per 9 innings.
What HR/9 means
The damage rate that separates otherwise similar arms. League average sits near 1.2; below 0.9 is a real skill, above 1.6 usually caps a pitcher's ceiling.
How HR/9 is calculated
HR/9 = HR × 9 / IP
What counts as a good HR/9
Lower is better — roughly 1.6 is poor, 1.25 average, 1 good, and .800 or better elite.
Also written
hr_per_9 · home_runs_per_9 · home_runs_per_9_inn