FantasyPros has put together a glossary of sabermetrics statistics for readers to reference. Deeper statistical analysis is being used by fantasy players more and more in daily and season-long leagues. We’re providing the glossary so that you can easily reference what the stats we use in our articles refer to and how they should be used for fantasy baseball purposes. Below we’ll take a look at BB/9.

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Walks per nine (BB/9) is a very simple calculation in which the amount of walks is divided by the amount of innings multiplied by nine. One key thing to look at is how thirds of an inning are calculated; 1/3 of an inning is .33 and 2/3 of an inning is .67. For reference, the MLB leader in BB/9 for 2015, Bartolo Colon, has one walk in 40 1/3 innings pitched. His walks per nine would be calculated as (1/40.33)*9, which equals a BB/9 of 0.223.

Many fantasy leagues use BB/9 as a statistic, and it is vital to comprehend this statistic for fantasy purposes. Fantasy leagues have trended to utilize more relievers to lower WHIP and ERA, so raw statistics like strikeouts and walks have yielded to K/9 and BB/9. As strikeouts have risen, control has diminshed, as only 12 of the top-100 BB/9 seasons all-time have been since 1950. Even though this is the case, Colon’s 0.223 BB/9 would be the best of all time, better than the current record set by George Zettlein in 1876 (0.231). Although it is very early in the season, Colon has only walked 1.3 batters per nine over the past four seasons. Doug Fister is the active leader in walks per nine for his career at 1.758, and Phil Hughes led baseball in walks per nine last season, allowing only 0.687 walks per nine. In five of the past six seasons, the MLB leader has had a walks per nine beneath 1.25.

Chris Zolli is a correspondent at FantasyPros. To read more from Chris, check out his archive and follow him @thezman2010.