The 1991 season in the Bull Baseball League was the first major formal reorganization of the league since it first formed in 1989. The season ran from about July to August 1991, and simulated a 30-game season, with two complete rounds of playoffs, both American Eagle League Championships and Lake League Championships, and a final Bull Cup Championship Series. The games were simulated using Earl Weaver Baseball software.
During the season, 12 Bull League teams played a 30-game schedule, with two rounds of playoffs following the end of the regular season.
The Bull Cup Championship was won by the Chicago Knights of the American Eagle League East division, who defeated the Boston Brawlers, 3-1.
American Eagle League
The season saw several major changes, including:
- Elimination of all historical player names from the league. Prior to 1991, real historical players like Bob Gibson and Sandy Koufax were on teams that also had fictional players. Some of these historical players were "retired" while others had their names changed to fictional ones.
- Team ownership was opened to individuals.
- Number of teams reduced to 12, divided into 4 divisions of three teams each.
- Central League was renamed to the Lake League and most teams were located in cities near the Great Lakes.
- Two rounds of playoffs, each a best-of-five format. The Bull Cup Championship Series was created, replacing the former Weaver Cup Championship Series, as well as the American Eagle League and Lake League Championship Series.