Yesterday I had a pretty good game with Dawn Guardian Varden and ran into a problem, a person cheating (imagine!).
He played some shietty scaling murloc build that got blown away pretty soon, but he wasn't taking lethal damage, he kept surviving as it was a tie. He also kept emoting so I know he was present during that time and not AFK.
I Managed to win around 12 combats before he outscaled and killed me, and thats probably how he got to the top 2. You can check out his name on the screenshot (also not surprising).
I must say that was a pretty neat little hack/cheat script, last time I saw something like this is when people used to turn into KT during combat and then "reconnect" during buy phase.
The people that reported "players turning into KT and back" also happened to be on mobile devices and those were bugs with the display. There is a server in between and I highly doubt that you can set your health to whatever you want from your client.
I don't know about the emoting but you only have one screenshot that doesn't really show much: did his board change? did the displayed history change? how much rating did you get at the end of the game?
PS: not sure what his name has to do with this? Because it's Cyrillic? I mean shad0wseek3er sounds rather fishy as well...