Duke began his career as a starter with the Pittsburgh Pirates in 2005. He was 45-70 with a 4.54 ERA in 159 starts. In 2009, when he was 11-16 with a 4.06 ERA, he made the National League All-Star team.
Duke, a Texas native who turns 36 in April, has bounced around the big leagues since last pitching for the Reds, playing for the Milwaukee Brewers, Chicago White Sox, Saint Louis Cardinals, Minnesota Twins and Seattle Mariners. Last season, he split time between Seattle and Minnesota and had a 4.15 ERA in 72 relief appearances.