Wood, 34, broke onto the scene in Chicago in 1998 when he posted a 13-6 record with a 3.40 ERA and 233 strikeouts in just 166.2 innings of work. He won the Rookie of the Year that season, but also gained notoriety for striking out 20 batters in one game.
GALLERY: BIGGEST SPORTS RETIREMENTS OF 2012
Wood did not pitch in 1999 due to an arm injury, but bounced back from 2001-2003 as a major force in a Cubs rotation that featured him and fellow young hurler Mark Prior. During that three-year span, Wood collected 12 or more wins, posted an ERA below 3.66, and struck out at least 217 batters in each season.