Sean O'Sullivan vs. Marsh Williams — Career Comparison

Looking at the career totals, Sean O'Sullivan and Marsh Williams are fairly close on the surface numbers. Sean O'Sullivan posted stronger numbers in ERA (6.01 vs 7.89) and WHIP (1.616 vs 1.987). Marsh Williams had the advantage in home runs allowed (0.7 per nine innings vs 1.64). By the career numbers, Sean O'Sullivan 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.