One thing that is a problem for many players is the division size. The problem arises when they are presented with 18 games at once. For many players, this is too much. For others, it is manageable, but it restricts the amount of other games that they play on the site.
Why not reduce the size of the divisions to 8, or even better, 6. 10 is a great number for football (soccer) divisions, because you play the games out over time. However, here, they just land on you with a thud. A division of 6 teams would promote two, relegate 2, and leave 2. It would also only have 10 games per person instead of 18.
Things this could accomplish...
1) Make it easier for smaller clans to have many teams in many leagues.
2) Increase the number of clan members willing to participate in leagues.
3) Decrease the number of clans that don't re-enlist their clans for subsequent seasons.
4) Reduce the total games played per league per season, which has the potential to reduce the season duration.
5) Increase the number of clan challenges and/or any other clan events that come up in the future.