The back of the card lists Heilman with the Seattle Mariners, but he never played for them. He was traded twice during the 2008-09 offseason, first from the Mets to the Mariners in December 2008, then again from the Mariners to the Cubs in January 2009. Topps had the back completed while he was still with Seattle, then they updated the front with a spring training photo with his new team. Since we don't know why Topps left the back as Seattle, it's considered a "design decision" and not marked as a UER.