[1] Like ERA, WHIP accounts for pitcher performance regardless of errors and unearned runs.
[note 1] The stat was invented in 1979 by writer Daniel Okrent,[1] who called the metric "innings pitched ratio" at the time.
The lowest single-season WHIP in MLB history through 2024 is held by George Walker of the 1940 Kansas City Monarchs, with a WHIP of 0.7347 which broke the previous record of 0.7692 of Guy Hecker of the 1882 Louisville Eclipse.
[4] Reliever Mariano Rivera ranks fourth among qualified pitchers with a career WHIP of 1.0003 in 1,2832⁄3 innings.
[4] Los Angeles Dodgers left-handed pitcher Clayton Kershaw ranks fifth with a WHIP of 1.0096 in 2,7422⁄3 innings.