In 2004, Johnston made the Pirates team out of spring training despite never previously pitching above the AA level.

By doing so, Johnston became the second known person with Tourette syndrome to play in Major League Baseball, after Jim Eisenreich.

That November, he signed a minor league contract with the San Diego Padres.

The Chicago White Sox signed him to a minor league contract for the 2009 season.

This biographical article relating to an American baseball pitcher born in the 1970s is a stub.