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 WHIP.

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WHIP stands for “walks and hits per inning pitched” and is quite basically just that; the number of walks and hits that a pitcher allows per inning he pitches. Compared to other advanced statistics, WHIP is incredibly easy to calculate and understand. The simple formula for WHIP is: (BB+H)/IP. This stat helps to give an idea of how effective a pitcher is at keeping runners off the bases. Obviously, the fewer baserunners a pitcher allows, the less likely he is to give up runs, especially “big innings.” WHIP does not include hit by pitch, despite the fact that it allows a runner on base. This is because when the stat was “invented,” hit batters were not listed in the following day’s newspaper box scores. HBPs are rare enough that they wouldn’t change a pitcher’s WHIP by much over the course of an entire season. WHIP, as opposed to ERA, factors a pitcher’s performance directly against batters, not taking into account errors and unearned runs. For reference, the lowest single-season WHIP of all-time belongs to Pedro Martinez, who posted a 0.74 WHIP in 2000. Pedro also holds the lowest career WHIP for pitchers in the live-ball era, a sterling 1.05.

So, that’s WHIP. But how can it help in fantasy? WHIP is already included in most 5×5 and 6×6 fantasy leagues, but it can help far beyond just being its own category. Pitchers with low WHIPs and high ERAs tend to see an improvement in their numbers, whereas pitchers with high WHIPs and low ERAs tend to regress. This makes sense, logically. A pitcher who does not allow many baserunners will not allow many runs, while a pitcher who allows many runners to reach base is much more likely to allow a lot of runs. While things like LOB% (percentage of runners a pitcher strands on base) and BABIP (batting average on balls in play) can skew things a bit, pitchers with low ERAs generally have low WHIPs, and pitchers with high ERAs generally have high WHIPs. For reference, the chart below shows how WHIP can be looked at over the course of a season (from Fangraphs):

WHIP is a stat that must be looked at carefully, as small sample size issues can occur. At the beginning of a season, a pitcher may get lit up during a rough start, which will inflate his WHIP immensely. While ERA may normalize a bit faster, WHIP can sometimes take a little longer to reach a projectable level. If a pitcher has a short start where he allows four runs on nine hits with two walks in three innings, then follows it up with six shutout innings, allowing six hits and two walks, his ERA will be a somewhat decent 4.00 while his WHIP will be an astronomical 2.11. You may look at a pitcher with a 4.00 ERA and think “decent,” whereas a 2.11 WHIP screams only “awful.”

WHIP is a nice, neat, simple sabermetric statistic that can be very helpful in predicting regression or improvement. Use it to buy low on guys with high ERAs and low WHIPs or to sell high on guys who have regression written all over them. Minor league WHIPs can also be used to project a prospect’s effectiveness after a call up. It basically boils down to this; a pitcher with a low WHIP tends to keep other things, like ERA, low as well. Pitchers with high WHIPs may perform well temporarily, but they are almost certainly doomed to regress before too long.

David A Marcillo is a correspondent at FantasyPros. To read more from David, check out his archive and follow him @DavidMarcillo77.