For what you're doing, the problem is that there's not always 2 numbers in the last 5 characters. A simple fix would be to omit the 5 character limit, and use as many characters as you need to get 2 numbers.
So if I take block 575970 for example: hash 00000000000000000010f46e3c11d28bd45958bb485fdaffad4de9dcadefff1c would mean "fff1c" and thus a "1" as winner in your system. I suggest to use the whole hash, and have "91" (00000000000000000010f46e3c11d28bd45958bb485fdaffad4de9dcadefff1c) as winner.
The account was hacked a few mounts ago and it looks like there is no way the owner to prove his ownership as the only ETH posted address was edited according to DarkStar_. I'll sent a PM anyway.