John Perkovich vs. Mariano Rivera — Career Comparison

On the career pitching numbers, Mariano Rivera posted a stronger line than John Perkovich. Mariano Rivera posted stronger numbers in ERA (2.21 vs 7.2) and WHIP (1.032 vs 1.600). By the career numbers, Mariano Rivera had the better of this comparison — though ERA and WHIP alone don't account for era, park factors, or the defenses each pitcher worked behind.