Home Run to Fly Ball Ratio (HR/FB) is a pitching statistic that measures the rate of home runs a pitcher gives up for each fly ball they allow.
HR/FB = home runs allowed / fly balls allowed
More about Pitcher Home Run to Fly Ball Ratio (HR/FB) Leaders
Pitching home run to fly ball ratio (HR/FB) leaders have the lowest percentage of all fly balls hit against them result in home runs. League leaders will generally have a HR/FB ratio of about 5%. Pitchers can limit the number of home runs allowed by limiting the total number of fly balls allowed, though pitchers are not thought to have a whole lot of control themselves as to what percentage of fly balls against turn into home runs. Pitchers who pitch more games in ballparks with deeper fences and thus more outfield grass are more likely to have a lower HR/FB ratio. A pitcher’s team outfield defense has limited impact on this ratio, as the only way they can boost a pitcher’s score is by “robbing” the opposing team of a home run by reaching over the fence to catch a would-be home run, which is not a common occurrence.