On this page
http://youplay.it/play/tn_Rules.asp beneath the table in the Special scoring system for Blue Max leagues section there is the line
For each side 1 point is awarded if there is a player who scored 15% more points of all his mate.
It took me a long while to find it

I think it should get a slight rewrite, so I'd suggest this
Best Player
In each game the best player, from each side with more than one player, will gain 1 league point if they score 15% more points than all of their teammates.
Actually, it's more accurate to say "any other teammate" rather than "all of their teammates", as the latter means you did better than all other team members combined.