Standing 6 feet 1 inch (185 cm) and weighing 185 pounds (84 kg),[1] he made his professional debut in 1984 for the minor-league Spartanburg Suns, an affiliate of the Philadelphia Phillies.

After battling arm injuries in the early 1990s, Jackson reestablished himself as a top relief pitcher for the Reds in 1995 and went on to pitch in the 1997 World Series for the Indians, for whom he then served as the full-time closer in 1998 and 1999.

[3] Jackson entered the Major League Baseball Draft in 1983, where he was selected by the Philadelphia Phillies in the 29th round.

[6] He played Triple-A ball for the Portland Beavers before making his major league debut for the Philadelphia Phillies on August 11, 1986.

For his debut, Jackson pitched a perfect inning in relief of Dan Schatzeder in a game against the New York Mets.

[8] Jackson played almost the entire 1987 season for the Philadelphia Phillies, also making two starts for the Maine Guides.

He was traded along with Glenn Wilson and Dave Brundage from the Phillies to the Seattle Mariners for Phil Bradley and Tim Fortugno at the Winter Meetings on December 9, 1987.

[11] In 1991, while facing the Kansas City Royals, he allowed Stu Cole's only Major League hit while pitching in the bottom of the 13th inning.

[12] After spending four seasons with the Mariners, Jackson was traded, along with Bill Swift and Dave Burba, to the San Francisco Giants in return for outfielder Kevin Mitchell and pitcher Mike Remlinger.

"[13] Jackson, now with a salary of $1,666,667,[1] made his debut for the Giants on April 7, 1992, in a game against the Los Angeles Dodgers.

Again he struggled with injury, and was placed on the disabled list once for tendinitis in his right shoulder and once for a strained rib cage muscle.

The Astros, National League Central champions, earned a spot in the playoffs, but were eliminated by the Atlanta Braves in the Divisional series.

After his season with the Astros, in 2002, Jackson signed as a non-roster invitee with the Minnesota Twins, helping them to finish 94–67 and leading them to a playoff appearance, where he recorded a 27.00 ERA over three games pitched in the American League Championship Series (ALCS).

If teams want to base their decision about me on spring training as opposed to what I’ve accomplished over the years, then I don’t know what to say.