Isaac Mattson vs. Willis Roberts — Career Comparison

On the career pitching numbers, Isaac Mattson posted a stronger line than Willis Roberts. Isaac Mattson posted stronger numbers in ERA (2.98 vs 4.64) and WHIP (1.256 vs 1.521). By the career numbers, Isaac Mattson 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.