Mark Mercer vs. Ryan Zeferjahn — Career Comparison

Looking at the career totals, Mark Mercer and Ryan Zeferjahn are fairly close on the surface numbers. Ryan Zeferjahn posted stronger numbers in ERA (4.14 vs 4.7) and WHIP (1.365 vs 1.826). Mark Mercer had the advantage in home runs allowed (1.17 per nine innings vs 1.46). By the career numbers, Ryan Zeferjahn 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.