Mariano Rivera vs. Grant Thatcher — Career Comparison

Looking at the career totals, Mariano Rivera and Grant Thatcher are fairly close on the surface numbers. Mariano Rivera posted stronger numbers in ERA (2.21 vs 3.16) and WHIP (1.032 vs 1.378). Grant Thatcher had the advantage in home runs allowed (0.24 per nine innings vs 0.5). By the career numbers, Mariano Rivera 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.