Clan ladder means that at least once per week all clans should play against each other. That's just impossible. Even in 'good old days' only few clanwars were played PER YEAR. It's quite funny, but all of the still 'active' clans don't play any clanwars now. Why? Because they are scary of losing and/or completing its best war team is hard or even impossible. I know what am I talking about because I have tried to arrange few clanwars lately. Actually only one clan accepted the challange, but setting the acceptable date for both teams already takes few weeks.

And you don't need to use system like JDC to this. There are many free scripts based on PHP and MySQL in the web which are good enough for such ladder and very easy in use. I was even thinking about making such ladder, but I have soon realized that it would be just useless.