John Callahan vs. Slim McGrew — Career Comparison

On the career pitching numbers, Slim McGrew posted a stronger line than John Callahan. Slim McGrew posted stronger numbers in ERA (6.6 vs 16.2) and WHIP (1.900 vs 3.000). By the career numbers, Slim McGrew 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.