Hey Kano, you need to add another rule to the contest.
Why? I suspect there's some users with a lot of hash power and they are making other accounts to split their hashpower.
Look at the workers. Users with almost the same name  
And i think 250TH is too high.
If you are somebody with 249TH you have enough money to buy an Avalon in 2-3 days.

IMHO