John Costello vs. Junior Guerra — Career Comparison

Junior Guerra built a career as a starting pitcher and John Costello as a reliever — different jobs with different demands — but on the metrics that apply to both, a comparison is still worth making. Junior Guerra led in home run suppression (HR9+ 123 vs 115), skill-based run prevention (DICE+ 105 vs 99), and strikeout rate (K%+ 101 vs 99). John Costello held the edge in run prevention (ERA+ 135 vs 124). Keeping the role difference in mind, the edge still goes to Junior Guerra.