Sean O'Sullivan vs. Mark Schaeffer — Career Comparison

Sean O'Sullivan built a career as a starting pitcher and Mark Schaeffer as a reliever — different jobs with different demands — but on the metrics that apply to both, a comparison is still worth making. Mark Schaeffer posted stronger surface numbers — ERA 4.61 and WHIP 2.000 compared to 6.01 and 1.616 for Sean O'Sullivan. By the career numbers, Mark Schaeffer had the better of this cross-role comparison — though era context would sharpen the verdict.