Ryan Mattheus vs. Sean O'Sullivan — Career Comparison

Sean O'Sullivan built a career as a starting pitcher and Ryan Mattheus as a reliever — different jobs with different demands — but on the metrics that apply to both, a comparison is still worth making. Ryan Mattheus posted stronger surface numbers — ERA 3.72 and WHIP 1.462 compared to 6.01 and 1.616 for Sean O'Sullivan. By the career numbers, Ryan Mattheus had the better of this cross-role comparison — though era context would sharpen the verdict.