<page_title> 1991 Oakland Athletics season </page_title> <section_title> Starting pitchers </section_title> <table> <cell> Bob Welch <col_header> Player </col_header> </cell> <cell> 4.58 <col_header> ERA </col_header> </cell> </table>
In the 1991 Oakland Athletics season, Bob Welch's earned run average was 4.58.