A lot of you might want to think carefully about whether those really are double-digit numbers of bitcoins the site claims you had.
As others have pointed out, the database on their site is corrupted, and some say 10000x figures are being shown.
Unless you were mining in late 2010 or early 2011 in a quite serious manner, or mining more recently with extremely huge mining rig arrays, then I don't see how you'd even have 10 BTC. And if you were leaving so much BTC on a pool well that is just bad practice. IIRC this pool encourage / had enabled by default autopayouts. So you are kind of to blame if you were using it like a bank and actually did have whole integer values of coins on the site...
To know exactly what people had on their account is a task that can be done. Some like myself may have a snapshot of the date before the "database" issue.
However for those that kept mining after the fact may be a little bit more difficult but not impossible.
For those coming here and publicly claiming that the corrupted total btc balance is correct and their claim proves false then those people are at risk of being prosecuted for fraud.
Remember that the account shares and stats were not compromised, only the account balance.
Knowing what each account balance is possible.