Description:

Homerun Rate (HR/FB) is the ratio of how many homeruns are hit against a pitcher for every flyball they allow. Homeruns are obviously not good for a pitcher, and a pitcher can reduce the number of homeruns hit against them in two ways: by increasing their groundball rate while lowering their flyball rate, or by reducing their HR/FB ratio. While pitchers can control (to an extent) the type of batted balls hit against them, there is less skill involved when considering whether a ball is hit into the seats or to the warning track. For example, pitchers that throw in a home ballpark with short fences will tend to have a higher homerun rate than pitchers that throw in large ballparks. Pitcher homerun rates have also been shown to vary considerably from year to year, meaning they have little predictive value.

Context:

League average homerun rate is normally around 10.6%, but it varies from year to year. For example, last season (“The Year of the Pitcher”) pitchers had a lower average homerun rate.

2010 HR/FB Rates

Things to Remember:

- Taking a glance at a pitcher’s homerun rate can help tell you if a player had an over- or under-inflated ERA. Pitchers with homerun rates much higher or lower than league average will normally regress towards league average in the future, which will have a corresponding effect on their ERAs and FIPs.

Links for Further Reading:

Platoon Splits, BABIP, and HR/FB rates – FanGraphs

The HR per FB Skill – The Book Blog

Groundballs and Home Run Rates – FanGraphs