He appeared in one game in Major League Baseball for the Toronto Blue Jays on September 18 during the 1998 season.

Withem attended Willow Run High School in Ypsilanti, Michigan where he was an all-state pitcher for the Flyers baseball team.

After going 17–5 with the Syracuse Chiefs, the Blue Jays' top farm team, he was called up in September.

In his lone major league appearance, he pitched three innings in relief of Kelvim Escobar, giving up one run on three hits with two walks and two strikeouts.

[2] After being released by the Blue Jays after the 1998 season, Withem signed with the Hokkaido Nippon-Ham Fighters in 1999.