In 1980, the 20-year-old became a regular on the team and began to produce in 1982, when he had 165 hits, 25 home runs and 105 RBIs. He ended the longest game in Major League history (eight hours and six minutes over 25 innings) with his home run off of the Milwaukee Brewers' Chuck Porter. That bat currently resides in the Baseball Hall of Fame.
In 1986, a succession of knee problems began that would end his fielding career, forcing him to become a regular designated hitter. However, despite the knee ailments, he remained a powerful hitter, picking up 166 hits in 1988.
Midway through the 1989 season, the Chicago White Sox traded Baines to the Texas Rangers in the infamous trade that included Sammy Sosa. In 1990, Baines was traded to the Oakland Athletics, where he helped them reach the post-season, only to be swept by the Cincinnati Reds in the World Series. In 1992, the Athletics returned to the playoffs only to lose to the Toronto Blue Jays in the ALCS.
Prior to the 1993 season, Baines was traded to the Baltimore Orioles. At the age of 34, Baines was still productive, hitting .313, .294 and .299 over his three seasons with the Os. Baines returned to the White Sox as a free agent in 1996 but was traded back to Baltimore midway through the 1997 season, where he helped the Orioles to reach the playoffs, where they lost to the Cleveland Indians in the League Championship Series.
His final contract with the Chicago White Sox was not renewed following the 2001 season after his third stint with the team. His number (#3) was retired by the White Sox following his initial departure from the city to Texas, but was "un-retired" twice following his two returns. He finished his career with 2,866 hits, 384 home runs and 1,628 RBIs.