After six years in the Tigers' system, spent mostly at the A-ball level, Brock was selected by the Seattle Mariners in the Rule 5 draft.

On April 8 of that year, Brock was signed by the Colorado Rockies and assigned to their AA affiliate, Carolina.

The Rockies in return obtained two prospects, John Cotton and Kevin Rawitzer, neither of whom made the major leagues.

He made his major league debut on March 29, 2000, appearing as a left fielder in the Cubs' Opening Day game against the New York Mets in the Tokyo Dome in Japan.

Brock played in the independent Northern League in 2001 and was named an All-Star, but a comeback in 2002 and 2003 with the Los Angeles Dodgers organization failed to get him back to the game's highest level.