Ernest Groth vs. Isaac Mattson — Career Comparison

On the career pitching numbers, Isaac Mattson posted a stronger line than Ernest Groth. Isaac Mattson posted stronger numbers in ERA (2.98 vs 4.91) and home runs allowed (0.63 per nine innings vs 2.45). 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.