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. In October 2006, Johnston underwent surgery to repair a torn labrum.
In 2004, Johnston was selected as the Pirates' starting pitcher during spring training despite never having pitched above the AA level. This made him the second known person with Tourette syndrome to play in Major League Baseball after Jim Eisenreich. In October 2006, Johnston underwent surgery to repair a torn labrum.