Brian O'Connor vs. Mike Willis — Career Comparison

On the career pitching numbers, Mike Willis posted a stronger line than Brian O'Connor. Mike Willis posted stronger numbers in ERA (4.59 vs 5.11) and WHIP (1.524 vs 1.865). By the career numbers, Mike Willis 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.