Kansas City maintained their reputation as one of the American League West's top contenders throughout the late 1980s. The club posted a winning record in three of the last four seasons following their World Series championship season. The Royals finished the 1989 season with a 90–70 record (third best record in franchise history) and a second place finish in the AL West seven games behind the season's World Series champion Oakland Athletics. Though the team boasted a powerhouse bullpen in the AL Cy Young Award winner Bret Saberhagen (set franchise record with 23 wins in 1989), two time All-Star Mark Gubicza (15 game winner in 1989) and 1989 AL Rookie of the Year runner-up Tom Gordon (won 17 games in 1989), the organization felt they were still missing a few pieces that would give the Oakland Athletics a run for their money.
The Royals were left without a caliber closing pitcher when Dan Quisenberry, the team's All-Star ace closer for much of the 1980s, was dropped from the club in 1988. Mark Davis, last season's league leader in saves (44) and boasting a 1.85 earned run average with the San Diego Padres, became a free agent at the close of the 1989 season. Kansas City had their eye on the 1989 National League Cy Young winner and back-to-back All-Star (1988, 1989), and after several attempts to acquire Davis, the organization was ultimately successful in signing him to a four-year $13 million contract (the largest annual salary in baseball history at the time). Several days earlier, the Royals bulked up their bullpen by inking starting pitcher Storm Davis, who was enjoying a career-high 19 game win record (3rd best in the league) with the Athletics in 1989, on a three-year $6 million contract. With a solid pitching rotation, which was now ranked among the best in the league, the team traded away starting pitcher Charlie Leibrandt and prospect Rick Luecken to the Atlanta Braves for 1988 All-Star first baseman Gerald Perry as an added offensive threat. The Royals filled in their fifth starting pitching slot by signing yet another free agent with veteran right-hander Richard Dotson. Kansas City concluded a milestone off-season as its biggest commitment to free agents in the club's entire history.
Despite the promising off-season moves, the team suffered critical bullpen injuries while the newly signed Davis hurlers both experienced lackluster performances throughout the season. The Royals concluded the 1990 campaign with a 75-86 finish and second-to-last place standing in the AL West (worst franchise record since 1970).  Though the team would bounce back with winning records during the next several years, the disastrous season would symbolically come to mark the beginning of the end of Kansas City's relevance in professional baseball.
George Brett became a three decade batting champ by winning the 1990 American League Batting Title.
July 11, 1990: In a game against the Baltimore Orioles, Bo Jackson performed his famous "wall run", when he caught a ball approximately 2-3 strides away from the wall. As he caught the ball at full tilt, Jackson looked up and noticed the wall and began to run up the wall, one leg reaching higher as he ascended. He ran along the wall almost parallel to the ground, and came down with the catch, to avoid impact and the risk of injury from the fence.