John Middleton vs. Sean O'Sullivan — Career Comparison

Looking at the career totals, John Middleton and Sean O'Sullivan are fairly close on the surface numbers. Sean O'Sullivan posted stronger numbers in ERA (6.01 vs 7.36) and WHIP (1.616 vs 1.909). John Middleton had the advantage in home runs allowed (1.23 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.