WHIP is one of the most commonly used statistics for evaluating a pitcher's performance. The statistic shows how well a pitcher has kept runners off the basepaths, one of his main goals. The formula is simple enough -- it's the sum of a pitcher's walks and hits, divided by his total innings pitched.
The pitchers with the lowest WHIPs are generally the best pitchers in the league -- which makes sense, because the best pitchers should be able to prevent baserunners. However, WHIP does not consider the way in which a hitter reached base. (Obviously, home runs are more harmful to pitchers than walks.)
Hit batsmen, errors and hitters who reach via fielder's choice do not count against a pitcher's WHIP.
Daniel Okrent, a writer who invented rotisserie league fantasy baseball, coined the term in 1979, initially calling it innings pitched ratio. The term eventually developed into WHIP.
In A Call
"whip" -- as an acronym, not spelled out