Jack Aker vs. Dan O'Brien — Career Comparison

Looking at the career totals, Jack Aker and Dan O'Brien are fairly close on the surface numbers. Jack Aker posted stronger numbers in ERA (3.28 vs 5.9) and WHIP (1.369 vs 1.931). Dan O'Brien had the advantage in home runs allowed (0.31 per nine innings vs 0.77). By the career numbers, Jack Aker 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.