The Mets acquired right-handed pitcher John Thomson from the Colorado Rockies at the 2002 trading deadline along with Mark Little in exchange for Jay Payton, Mark Corey and Robert Stratton. He made his Mets debut on August 3 against the Arizona Diamondbacks and was the losing pitcher in the Mets 9-2 loss; he allowed 7 runs, 3 of which were earned over 6 innings. He would lose his first three starts for the Mets before recording his first win on August 27 against the Florida Marlins. Overall Thomson started 9 games for the Mets and finished with a 2-6 record and 4.31 ERA.
Following the season Thomson signed as a free agent with the Texas Rangers.
While with the Mets Thomson wore number 50.
John Thomson also played for the following teams:
Colorado Rockies – 1997-1999, 2001,2002
Texas Rangers – 2003
Atlanta Braves – 2004-2006
Kansas City Royals – 2007