Before the 1998 regular season began, two new teams—the Arizona Diamondbacks and Tampa Bay Devil Rays—were added by Major League Baseball. This resulted in the American League and National League having fifteen teams. However, in order for MLB officials to continue primarily intraleague play, both leagues would need to carry a number of teams that was divisible by two, so the decision was made to move one club from the AL Central to the NL Central.
This realignment was widely considered to have great financial benefit to the club moving. However, to avoid the appearance of a conflict of interest, Commissioner (then club owner) Bud Selig decided another team should have the first chance to switch leagues. The choice was offered to the Kansas City Royals, who ultimately decided to stay in the American League. The choice then fell to the Brewers, who, on November 6, 1997 elected to move to the National League. Had the Brewers elected not to move to the National League, the Minnesota Twins would have been offered the opportunity to switch leagues.