Complex sentence: Traditionally, the CFL and Arena Football have scheduled byes only in seasons when they have had an odd number of teams in their leagues, however the CFL introduced a scheduled bye week for its (currently eight) teams for the 2007 season.
Split into simpler sentences: Traditionally, the CFL and Arena Football have scheduled byes only in seasons when they have had an odd number of teams in their leagues. However, the CFL introduced a scheduled bye week for its (currently eight) teams for the 2007 season.