Jokes aside, this has become an embarrasing "habit" or "bad streak" of ours with such mishaps. The game was arranged quite hastily and IPL_SerGrzybek is member of our clan since 2010 so we were quite sure that Volv didn't miss him when he was registering our team. I mean I believe he was signed up in the previous tournament... This is his steam account link:
https://steamcommunity.com/profiles/76561198017051025/ and I will drag Volv here to re-examine our roster and make an official post in proper roster thread filling up whoever he left out while signing us up.
I once again apologise for this mess as it is entirely on our side.
EDIT: Yes, SerGrzybek was signed up in the first edition (
https://forums.taleworlds.com/index.php?threads/beast-1-rosters.424786/post-9455732). So I have no idea how did it happen that Volv forgot to sign him up here... quite amazing in fact.