The Metric of Traffic Control
While Earned Run Average (ERA) tells you the end result of a pitcher's performance (how many runs scored), it doesn't tell you how those runs scored. A pitcher can have a deceptively decent ERA while constantly pitching out of massive, self-inflicted danger.
In 1979, writer Daniel Okrent invented Walks and Hits Per Inning Pitched (WHIP) to solve this. WHIP directly measures how much "traffic" a pitcher allows on the basepaths.
The Beauty of Simplicity
WHIP is arguably the purest measurement of a pitcher's command and control. It ignores home runs and fielding errors, focusing entirely on how many baserunners the pitcher allows per inning.
The Formula
The calculation simply adds the two most common ways a batter reaches base, and divides by the innings pitched.
WHIP = (Walks + Hits) / Innings Pitched
Evaluating the Damage
- 1.00 or lower: Absolute dominance. The pitcher is allowing an average of only one baserunner per inning, making it mathematically nearly impossible for the opposing team to string together enough hits to score runs.
- 1.30: League average.
- 1.50+: A disaster. The pitcher is constantly pitching with multiple runners on base, operating under extreme stress on every single pitch.