Manage tournament brackets
There are some types of events where you can't forecast the competitors such as a single elimination tournament. You may know the first set of competitors, but after the first round of games you can't predict who a team will play against next.
Also, some leagues use a ranking system to identify who the next competitor would be, which is dependent on the previous match results. This would fairly assign competitors to a match so that a #2 ranked competitor wouldn't be matched against a #30 ranked competitor for example.