Mysterious Walker
... that Mysterious Walker, who played for or coached more than 30 baseball, basketball and football teams, earned his nickname pitching for the San Francisco Seals under a pseudonym and wearing a mask?
... that <b id="mwA8A"><a href="./Mysterious_Walker" id="mwA8E" rel="mw:WikiLink" title="Mysterious Walker">Mysterious Walker</a></b>, who played for or coached more than 30 <a href="./Baseball" id="mwA8I" rel="mw:WikiLink" title="Baseball">baseball</a>, <a href="./Basketball" id="mwA8M" rel="mw:WikiLink" title="Basketball">basketball</a> and <a href="./American_football" id="mwA8Q" rel="mw:WikiLink" title="American football">football</a> teams, earned his nickname pitching for the <a class="mw-redirect" href="./San_Francisco_Seals_(baseball)" id="mwA8U" rel="mw:WikiLink" title="San Francisco Seals (baseball)">San Francisco Seals</a> under a pseudonym and wearing a mask?